Skip to content

[LibCall] Infer nocallback for libcalls #135173

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Merged
merged 4 commits into from
Apr 12, 2025
Merged

[LibCall] Infer nocallback for libcalls #135173

merged 4 commits into from
Apr 12, 2025

Conversation

@dtcxzyw
Copy link
Member

@dtcxzyw dtcxzyw commented Apr 10, 2025 •
edited
Loading

This patch adds nocallback attributes for string/math libcalls. It allows FuncAttributor to infer norecurse more precisely and encourages more aggressive global optimization.

This was referenced Apr 10, 2025
Open
Closed
@dtcxzyw dtcxzyw marked this pull request as ready for review April 10, 2025 17:07
@llvmbot llvmbot added backend:X86 llvm:instcombine Covers the InstCombine, InstSimplify and AggressiveInstCombine passes llvm:transforms labels Apr 10, 2025
@llvmbot
Copy link
Member

llvmbot commented Apr 10, 2025

@llvm/pr-subscribers-backend-x86

Author: Yingwei Zheng (dtcxzyw)

Changes

This patch adds nocallback attributes for most of libcalls (except for exit/terminate/qsort/signal/...). It allows FuncAttributor to infer norecurse more precisely and encourages more aggressive global optimization.

Patch is 53.30 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/135173.diff

12 Files Affected:

  • (modified) llvm/lib/Transforms/Utils/BuildLibCalls.cpp (+122-1)
  • (modified) llvm/test/CodeGen/X86/no-plt-libcalls.ll (+1-1)
  • (modified) llvm/test/Transforms/InferFunctionAttrs/annotate.ll (+34-33)
  • (modified) llvm/test/Transforms/InferFunctionAttrs/readonly_and_writeonly.ll (+1-1)
  • (modified) llvm/test/Transforms/InstCombine/printf-2.ll (+1-1)
  • (modified) llvm/test/Transforms/LICM/strlen.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/basic.ll (+1-2)
  • (modified) llvm/test/Transforms/LoopIdiom/memset-pattern-tbaa.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/struct_pattern.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/unroll-custom-dl.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/unroll.ll (+1-1)
  • (modified) llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll (+1-1)
diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index 24eefc91117b4..88704d689c3b1 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -47,6 +47,7 @@ STATISTIC(
     NumWriteArgumentMemOrErrnoMemOnly,
     "Number of functions inferred as memory(argmem: write, errnomem: write)");
 STATISTIC(NumNoUnwind, "Number of functions inferred as nounwind");
+STATISTIC(NumNoCallback, "Number of functions inferred as nocallback");
 STATISTIC(NumNoCapture, "Number of arguments inferred as nocapture");
 STATISTIC(NumWriteOnlyArg, "Number of arguments inferred as writeonly");
 STATISTIC(NumReadOnlyArg, "Number of arguments inferred as readonly");
@@ -148,6 +149,14 @@ static bool setDoesNotThrow(Function &F) {
   return true;
 }
 
+static bool setDoesNotCallback(Function &F) {
+  if (F.hasFnAttribute(Attribute::NoCallback))
+    return false;
+  F.addFnAttr(Attribute::NoCallback);
+  ++NumNoCallback;
+  return true;
+}
+
 static bool setRetDoesNotAlias(Function &F) {
   if (F.hasRetAttribute(Attribute::NoAlias))
     return false;
@@ -322,6 +331,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_wcslen:
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -331,6 +341,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     break;
   case LibFunc_strtol:
@@ -341,6 +352,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strtold:
   case LibFunc_strtoull:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -349,6 +361,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strncat:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setReturnedArg(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -364,6 +377,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_stpncpy:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -373,6 +387,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_strxfrm:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -383,6 +398,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strncmp:     // 0,1
   case LibFunc_strcspn:     // 0,1
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyReadsMemory(F);
@@ -396,6 +412,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     // global memory.
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -405,12 +422,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_strtok:
   case LibFunc_strtok_r:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -418,6 +437,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_scanf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
@@ -425,6 +445,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_setvbuf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_strndup:
@@ -434,6 +455,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setAllocFamily(F, "malloc");
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -443,6 +465,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_statvfs:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -450,6 +473,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_sscanf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -458,6 +482,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_sprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -467,6 +492,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_snprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -476,6 +502,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_setitimer:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setDoesNotCapture(F, 2);
@@ -483,6 +510,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_system:
     // May throw; "system" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -502,6 +530,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
@@ -509,6 +538,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -516,6 +546,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_memchr:
   case LibFunc_memrchr:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
@@ -524,6 +555,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_modff:
   case LibFunc_modfl:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyWritesMemory(F);
@@ -531,6 +563,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_memcpy:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotAlias(F, 0);
@@ -542,6 +575,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_memmove:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setReturnedArg(F, 0);
@@ -555,6 +589,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     [[fallthrough]];
   case LibFunc_memcpy_chk:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -571,18 +606,21 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
   case LibFunc_mkdir:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_mktime:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -597,6 +635,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -610,6 +649,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -618,12 +658,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_read:
     // May throw; "read" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_rewind:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_rmdir:
@@ -631,12 +673,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_realpath:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_rename:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -645,18 +689,21 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_readlink:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_write:
     // May throw; "write" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
     break;
   case LibFunc_bcopy:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -666,6 +713,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_bcmp:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
@@ -674,6 +722,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_bzero:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -688,6 +737,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
@@ -695,6 +745,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_chown:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
@@ -703,6 +754,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_closedir:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_atoi:
@@ -710,6 +762,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_atof:
   case LibFunc_atoll:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -717,12 +770,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_access:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_fopen:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -732,6 +787,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fdopen:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -739,6 +795,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_feof:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_free:
@@ -750,6 +807,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -768,11 +826,13 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_ftrylockfile:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_ferror:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F);
     break;
@@ -781,12 +841,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fstat:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_frexp:
   case LibFunc_frexpf:
   case LibFunc_frexpl:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyWritesMemory(F);
@@ -795,12 +857,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fstatvfs:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_fgets:
   case LibFunc_fgets_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 2);
     Changed |= setOnlyWritesMemory(F, 0);
     break;
@@ -808,6 +872,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fread_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 3);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -816,6 +881,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fwrite_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 3);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -824,6 +890,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fputs_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -832,6 +899,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -839,27 +907,32 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fgetpos:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_getc:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getlogin_r:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getc_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getenv:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -868,37 +941,44 @@ bool llvm::inferNonMandatoryLibFuncAttr...
[truncated]

@llvmbot
Copy link
Member

llvmbot commented Apr 10, 2025

@llvm/pr-subscribers-llvm-transforms

Author: Yingwei Zheng (dtcxzyw)

Changes

This patch adds nocallback attributes for most of libcalls (except for exit/terminate/qsort/signal/...). It allows FuncAttributor to infer norecurse more precisely and encourages more aggressive global optimization.

Patch is 53.30 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/135173.diff

12 Files Affected:

  • (modified) llvm/lib/Transforms/Utils/BuildLibCalls.cpp (+122-1)
  • (modified) llvm/test/CodeGen/X86/no-plt-libcalls.ll (+1-1)
  • (modified) llvm/test/Transforms/InferFunctionAttrs/annotate.ll (+34-33)
  • (modified) llvm/test/Transforms/InferFunctionAttrs/readonly_and_writeonly.ll (+1-1)
  • (modified) llvm/test/Transforms/InstCombine/printf-2.ll (+1-1)
  • (modified) llvm/test/Transforms/LICM/strlen.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/basic.ll (+1-2)
  • (modified) llvm/test/Transforms/LoopIdiom/memset-pattern-tbaa.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/struct_pattern.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/unroll-custom-dl.ll (+1-1)
  • (modified) llvm/test/Transforms/LoopIdiom/unroll.ll (+1-1)
  • (modified) llvm/test/Transforms/PreISelIntrinsicLowering/X86/memset-pattern.ll (+1-1)
diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index 24eefc91117b4..88704d689c3b1 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -47,6 +47,7 @@ STATISTIC(
     NumWriteArgumentMemOrErrnoMemOnly,
     "Number of functions inferred as memory(argmem: write, errnomem: write)");
 STATISTIC(NumNoUnwind, "Number of functions inferred as nounwind");
+STATISTIC(NumNoCallback, "Number of functions inferred as nocallback");
 STATISTIC(NumNoCapture, "Number of arguments inferred as nocapture");
 STATISTIC(NumWriteOnlyArg, "Number of arguments inferred as writeonly");
 STATISTIC(NumReadOnlyArg, "Number of arguments inferred as readonly");
@@ -148,6 +149,14 @@ static bool setDoesNotThrow(Function &F) {
   return true;
 }
 
+static bool setDoesNotCallback(Function &F) {
+  if (F.hasFnAttribute(Attribute::NoCallback))
+    return false;
+  F.addFnAttr(Attribute::NoCallback);
+  ++NumNoCallback;
+  return true;
+}
+
 static bool setRetDoesNotAlias(Function &F) {
   if (F.hasRetAttribute(Attribute::NoAlias))
     return false;
@@ -322,6 +331,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_wcslen:
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -331,6 +341,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     break;
   case LibFunc_strtol:
@@ -341,6 +352,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strtold:
   case LibFunc_strtoull:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -349,6 +361,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strncat:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setReturnedArg(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -364,6 +377,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_stpncpy:
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -373,6 +387,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_strxfrm:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -383,6 +398,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_strncmp:     // 0,1
   case LibFunc_strcspn:     // 0,1
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyReadsMemory(F);
@@ -396,6 +412,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     // global memory.
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -405,12 +422,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_strtok:
   case LibFunc_strtok_r:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -418,6 +437,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_scanf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
@@ -425,6 +445,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_setvbuf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_strndup:
@@ -434,6 +455,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setAllocFamily(F, "malloc");
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -443,6 +465,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_statvfs:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -450,6 +473,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_sscanf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -458,6 +482,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_sprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -467,6 +492,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_snprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -476,6 +502,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_setitimer:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setDoesNotCapture(F, 2);
@@ -483,6 +510,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_system:
     // May throw; "system" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -502,6 +530,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
@@ -509,6 +538,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -516,6 +546,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_memchr:
   case LibFunc_memrchr:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
@@ -524,6 +555,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_modff:
   case LibFunc_modfl:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyWritesMemory(F);
@@ -531,6 +563,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_memcpy:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotAlias(F, 0);
@@ -542,6 +575,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_memmove:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setReturnedArg(F, 0);
@@ -555,6 +589,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     [[fallthrough]];
   case LibFunc_memcpy_chk:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setDoesNotAlias(F, 0);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -571,18 +606,21 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
   case LibFunc_mkdir:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_mktime:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -597,6 +635,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -610,6 +649,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -618,12 +658,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_read:
     // May throw; "read" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_rewind:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_rmdir:
@@ -631,12 +673,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_realpath:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_rename:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -645,18 +689,21 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_readlink:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_write:
     // May throw; "write" is a valid pthread cancellation point.
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
     break;
   case LibFunc_bcopy:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -666,6 +713,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_bcmp:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
@@ -674,6 +722,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     break;
   case LibFunc_bzero:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -688,6 +737,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setWillReturn(F);
     break;
@@ -695,6 +745,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_chown:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
@@ -703,6 +754,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_closedir:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_atoi:
@@ -710,6 +762,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_atof:
   case LibFunc_atoll:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
@@ -717,12 +770,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_access:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F, 0);
     break;
   case LibFunc_fopen:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
@@ -732,6 +787,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fdopen:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setRetDoesNotAlias(F);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -739,6 +795,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_feof:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_free:
@@ -750,6 +807,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -768,11 +826,13 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_ftrylockfile:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_ferror:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setOnlyReadsMemory(F);
     break;
@@ -781,12 +841,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fstat:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_frexp:
   case LibFunc_frexpf:
   case LibFunc_frexpl:
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setWillReturn(F);
     Changed |= setOnlyAccessesArgMemory(F);
     Changed |= setOnlyWritesMemory(F);
@@ -795,12 +857,14 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fstatvfs:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_fgets:
   case LibFunc_fgets_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 2);
     Changed |= setOnlyWritesMemory(F, 0);
     break;
@@ -808,6 +872,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fread_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 3);
     Changed |= setOnlyWritesMemory(F, 0);
@@ -816,6 +881,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fwrite_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 3);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -824,6 +890,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fputs_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 0);
@@ -832,6 +899,7 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fprintf:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     Changed |= setOnlyReadsMemory(F, 1);
@@ -839,27 +907,32 @@ bool llvm::inferNonMandatoryLibFuncAttrs(Function &F,
   case LibFunc_fgetpos:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     Changed |= setDoesNotCapture(F, 1);
     break;
   case LibFunc_getc:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getlogin_r:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getc_unlocked:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
   case LibFunc_getenv:
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
+    Changed |= setDoesNotCallback(F);
     Changed |= setOnlyReadsMemory(F);
     Changed |= setDoesNotCapture(F, 0);
     break;
@@ -868,37 +941,44 @@ bool llvm::inferNonMandatoryLibFuncAttr...
[truncated]

antoniofrighetto
antoniofrighetto approved these changes Apr 10, 2025
View reviewed changes
Copy link
Contributor

@antoniofrighetto antoniofrighetto left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

LGTM (glibc used to support malloc/free user hooks, but even in that case, I don't think it would be too much of an issue).

@dtcxzyw
Copy link
Member Author

dtcxzyw commented Apr 11, 2025

glibc used to support malloc/free user hooks, but even in that case, I don't think it would be too much of an issue

While GNU memory allocation hooks were deprecated in glibc 2.34, other memory allocators (e.g., mimalloc/jemalloc) still provide some kinds of callback mechanisms :(

nikic
nikic requested changes Apr 11, 2025
View reviewed changes
Copy link
Contributor

@nikic nikic left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

At least a lot of the FS stuff here is wrong due to fopencookie.

nikic
nikic reviewed Apr 11, 2025
View reviewed changes
nikic
nikic reviewed Apr 11, 2025
View reviewed changes
Copy link
Contributor

@nikic nikic left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Generally, I'd be a lot more comfortable if this were limited to the "obvious" stuff (like memcmp not going to call back to user code) and skip everything syscall related.

@dtcxzyw dtcxzyw merged commit 76e07d8 into llvm:main Apr 12, 2025
11 checks passed
@dtcxzyw dtcxzyw deleted the perf/nocallback branch April 12, 2025 07:11
@llvm-ci
Copy link
Collaborator

llvm-ci commented Apr 12, 2025

LLVM Buildbot has detected a new failure on builder openmp-s390x-linux running on systemz-1 while building llvm at step 6 "test-openmp".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/88/builds/10344

Here is the relevant piece of the build log for the reference 
Step 6 (test-openmp) failure: test (failure)
******************** TEST 'libomp :: tasking/issue-94260-2.c' FAILED ********************
Exit Code: -11

Command Output (stdout):
--
# RUN: at line 1
/home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/./bin/clang -fopenmp   -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test -L /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src  -fno-omit-frame-pointer -mbackchain -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/ompt /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/tasking/issue-94260-2.c -o /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp -lm -latomic && /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp
# executed command: /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/./bin/clang -fopenmp -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test -L /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/src -fno-omit-frame-pointer -mbackchain -I /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/ompt /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.src/openmp/runtime/test/tasking/issue-94260-2.c -o /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp -lm -latomic
# executed command: /home/uweigand/sandbox/buildbot/openmp-s390x-linux/llvm.build/runtimes/runtimes-bins/openmp/runtime/test/tasking/Output/issue-94260-2.c.tmp
# note: command had no output on stdout or stderr
# error: command failed with exit status: -11

--

********************

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@nikic nikic nikic approved these changes

@antoniofrighetto antoniofrighetto antoniofrighetto approved these changes

@efriedma-quic efriedma-quic Awaiting requested review from efriedma-quic

Assignees

No one assigned

Labels

backend:X86 llvm:instcombine Covers the InstCombine, InstSimplify and AggressiveInstCombine passes llvm:transforms

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

5 participants

@dtcxzyw @llvmbot @llvm-ci @nikic @antoniofrighetto