simplify test. The next step is to add debug log

Author: mingmingl-llvm

llvm/include/llvm/Analysis/StaticDataProfileInfo.h

@@ -10,6 +10,8 @@
 
 namespace llvm {
 
+bool IsReservedGlobalVariable(const GlobalVariable &GV);
+
 /// A class that holds the constants that represent static data and their
 /// profile information and provides methods to operate on them.
 class StaticDataProfileInfo {

llvm/lib/Analysis/StaticDataProfileInfo.cpp

@@ -14,6 +14,10 @@ using namespace llvm;
 
 extern cl::opt<bool> AnnotateStaticDataSectionPrefix;
 
+bool llvm::IsReservedGlobalVariable(const GlobalVariable &GV) {
+  return GV.getName().starts_with("llvm.");
+}
+
 void StaticDataProfileInfo::addConstantProfileCount(
     const Constant *C, std::optional<uint64_t> Count) {
   if (!Count) {
@@ -87,7 +91,8 @@ StringRef StaticDataProfileInfo::getConstantSectionPrefix(
     // Module flag `HasDataAccessProf` is 1 -> empty section prefix means
     // unknown hotness except for string literals.
     if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C);
-        GV && !GV->getName().starts_with(".str")) {
+        GV && !IsReservedGlobalVariable(*GV) &&
+        !GV->getName().starts_with(".str")) {
       auto HotnessFromDAP = getSectionHotnessUsingDAP(GV->getSectionPrefix());
 
       if (!Count) {

llvm/lib/CodeGen/StaticDataSplitter.cpp

@@ -133,8 +133,7 @@ StaticDataSplitter::getConstant(const MachineOperand &Op,
     // Skip 'llvm.'-prefixed global variables conservatively because they are
     // often handled specially, and skip those not in static data
     // sections.
-    if (!GV || GV->getName().starts_with("llvm.") ||
-        !inStaticDataSection(*GV, TM))
+    if (!GV || llvm::IsReservedGlobalVariable(*GV) || !inStaticDataSection(*GV, TM))
       return nullptr;
     return GV;
   }

llvm/test/CodeGen/X86/global-variable-partition-dap.ll

@@ -2,136 +2,99 @@ target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:
 target triple = "x86_64-unknown-linux-gnu"
 
 ;; Comments for RUN command options
-; 1. `-relocation-model=pic` -> `hot_relro_array` and `cold_relro_array` are
+; 1. `-relocation-model=pic` -> `relro_var` is 
 ;    placed in the .data.rel.ro-prefixed section.
 ; 2. `-data-sections=true -unique-section-names=false` -> data sections are
 ;    uniqufied by variable names.
 ;
 ; RUN: llc -mtriple=x86_64-unknown-linux-gnu -relocation-model=pic \
 ; RUN:     -partition-static-data-sections=true \
 ; RUN:     -data-sections=true  -unique-section-names=false \
-; RUN:     %s -o - 2>&1 | FileCheck %s --check-prefixes=UNIQ,COMMON --dump-input=always
+; RUN:     %s -o - 2>&1 | FileCheck %s  --dump-input=always
 
 ; For @.str and @.str.1
-; COMMON:      .type .L.str,@object
-; UNIQ-NEXT:   .section	.rodata.str1.1.hot.,"aMS",@progbits,1
-; COMMON-NEXT: .L.str:
-; COMMON-NEXT:    "hot\t"
-; COMMON:      .L.str.1:
-; COMMON-NEXT:    "%d\t%d\t%d\n"
+; CHECK:      .type .L.str,@object
+; CHECK-NEXT:   .section	.rodata.str1.1.hot.,"aMS",@progbits,1
+; CHECK-NEXT: .L.str:
+; CHECK-NEXT:    "1234"
+; CHECK:      .type .str.1,@object
+; CHECK:      .str.1:
+; CHECK-NEXT:    "abcde"
 
-; For @hot_relro_array
-; COMMON:      .type hot_relro_array,@object
-; UNIQ-NEXT:   .section	.data.rel.ro.hot.,"aw",@progbits,unique,1
+; For @.str.2
+; CHECK:      .type .str.2,@object
+; CHECK-NEXT:   .section	.rodata.str1.1,"aMS",@progbits
+; CHECK-NEXT:  .globl .str.2
+; CHECK-NEXT: .str.2:
+; CHECK-NEXT:    "beef"
+@.str = private unnamed_addr constant [5 x i8] c"1234\00", align 1
+@.str.1 = internal unnamed_addr constant [6 x i8] c"abcde\00"
+@.str.2 = unnamed_addr constant [5 x i8] c"beef\00", align 1
 
-; For @external_hot_data, which is accessed by {cold_func, unprofiled_func, hot_func}.
-; COMMON:      .type external_hot_data,@object
-; UNIQ-NEXT:   .section	.data.hot.,"aw",@progbits,unique,2
+; CHECK:      .type relro_var,@object
+; CHECK-NEXT:   .section	.data.rel.ro,"aw",@progbits,unique,1
 
-; For @hot_bss, which is accessed by {unprofiled_func, hot_func}.
-; COMMON:      .type hot_bss,@object
-; UNIQ-NEXT:   .section	.bss.hot.,"aw",@nobits,unique,3
+; CHECK:      .type external_hot_data,@object
+; CHECK-NEXT:   .section	.data.hot.,"aw",@progbits,unique,2
 
-; For @.str.2
-; COMMON:      .type .L.str.2,@object
-; UNIQ-NEXT:   .section	.rodata.str1.1.unlikely.,"aMS",@progbits,1
-; COMMON-NEXT: .L.str.2:
-; COMMON-NEXT:    "cold%d\t%d\t%d\n"
-
-; For @cold_bss
-; COMMON:      .type cold_bss,@object
-; UNIQ-NEXT:   .section	.bss.unlikely.,"aw",@nobits,unique,4
-
-; For @cold_data
-; COMMON:      .type cold_data,@object
-; UNIQ-NEXT:   .section	.data.unlikely.,"aw",@progbits,unique,5
-
-; For @cold_data_custom_foo_section
-; It has an explicit section 'foo' and shouldn't have hot or unlikely suffix.
-; COMMON:      .type cold_data_custom_foo_section,@object
-; UNIQ-NEXT:   .section foo,"aw",@progbits
-
-; For @cold_relro_array
-; COMMON:      .type cold_relro_array,@object
-; UNIQ-NEXT:   .section	.data.rel.ro.unlikely.,"aw",@progbits,unique,6
-
-
-; @bss2 and @data3 are indirectly accessed via @hot_relro_array and
-; @cold_relro_array, and actually hot due to accesses via @hot_relro_array.
-; Under the hood, the static data splitter pass analyzes accesses from code but
-; won't aggressively propgate the hotness of @hot_relro_array into the array
-; elements -- instead, this pass reconciles the hotness information from both
-; global variable section prefix and PGO counters.
-
-; @bss2 has a section prefix 'hot' in the IR. StaticDataProfileInfo reconciles
-; it into a hot prefix.
-; COMMON:      .type bss2,@object
-; UNIQ-NEXT:   .section	.bss.hot.,"aw",@nobits,unique,7
-
-; @data3 doesn't have data access profile coverage and thereby doesn't have a
-; section prefix. PGO counter analysis categorizes it as cold, so it will have
-; section name `.data.unlikely`.
-; COMMON:      .type data3,@object
-; UNIQ-NEXT:   .section	.data,"aw",@progbits,unique,8
-
-; For @data_with_unknown_hotness
-; COMMON: 	       .type	.Ldata_with_unknown_hotness,@object          # @data_with_unknown_hotness
-; UNIQ:        .section  .data,"aw",@progbits,unique,9
-
-; For @hot_data_custom_bar_section
-; It has an explicit section attribute 'var' and shouldn't have hot or unlikely suffix.
-; COMMON:      .type hot_data_custom_bar_section,@object
-; UNIQ:        .section bar,"aw",@progbits
-
-; For @external_cold_bss
-; COMMON:      .type external_cold_bss,@object
-; UNIQ-NEXT:   .section	.bss,"aw",@nobits,unique,
-
-@.str = private unnamed_addr constant [5 x i8] c"hot\09\00", align 1
-@.str.1 = private unnamed_addr constant [10 x i8] c"%d\09%d\09%d\0A\00", align 1
-@hot_relro_array = internal constant [2 x ptr] [ptr @bss2, ptr @data3]
+; CHECK:      .type hot_bss,@object
+; CHECK-NEXT:   .section	.bss.hot.,"aw",@nobits,unique,3
+
+@relro_var = constant [2 x ptr] [ptr @bss2, ptr @data3]
 @external_hot_data = global i32 5, !section_prefix !17
 @hot_bss = internal global i32 0
-@.str.2 = private unnamed_addr constant [14 x i8] c"cold%d\09%d\09%d\0A\00", align 1
+
+;; Both section prefix and PGO counters indicate @cold_bss and @cold_data are
+;; rarely accesed.
+; CHECK:      .type cold_bss,@object
+; CHECK-NEXT:   .section	.bss.unlikely.,"aw",@nobits,unique,4
+; CHECK:      .type cold_data,@object
+; CHECK-NEXT:   .section	.data.unlikely.,"aw",@progbits,unique,5
 @cold_bss = internal global i32 0, !section_prefix !18
 @cold_data = internal global i32 4, !section_prefix !18
-@cold_data_custom_foo_section = internal global i32 100, section "foo"
-@cold_relro_array = internal constant [2 x ptr] [ptr @data3, ptr @bss2], !section_prefix !18
+
+;; @bss2 has a section prefix 'hot' in the IR. StaticDataProfileInfo reconciles
+;; it into a hot prefix.
+; CHECK:      .type bss2,@object
+; CHECK-NEXT:   .section	.bss.hot.,"aw",@nobits,unique,6
 @bss2 = internal global i32 0, !section_prefix !17
+
+;; Since `HasDataAccessProf` is true, data without a section prefix is
+;; conservatively categorized as unknown (e.g., from incremental source code)
+;; rather than cold.
+; CHECK:      .type data3,@object
+; CHECK-NEXT:   .section	.data,"aw",@progbits,unique,7
 @data3 = internal global i32 3
-@data_with_unknown_hotness = private global i32 5
+
+;; These sections have custom names, so they won't be labeled as .hot or .unlikely.
+; CHECK:      .type hot_data_custom_bar_section,@object
+; CHECK-NEXT:    .section bar,"aw"
+; CHECK:      .type cold_data_custom_foo_section,@object
+; CHECK-NEXT:   .section foo,"aw"
 @hot_data_custom_bar_section = internal global i32 101 #0
-@external_cold_bss = global i32 0
+@cold_data_custom_foo_section = internal global i32 100, section "foo"
 
 define void @cold_func(i32 %0) !prof !15 {
   %2 = load i32, ptr @cold_bss
   %3 = load i32, ptr @cold_data
-  %4 = srem i32 %0, 2
-  %5 = sext i32 %4 to i64
-  %6 = getelementptr inbounds [2 x ptr], ptr @cold_relro_array, i64 0, i64 %5
-  %7 = load ptr, ptr %6
-  %8 = load i32, ptr %7
-  %9 = load i32, ptr @data_with_unknown_hotness
   %11 = load i32, ptr @external_hot_data
   %12 = load i32, ptr @cold_data_custom_foo_section
-  %val = load i32, ptr @external_cold_bss
-  %13 = call i32 (...) @func_taking_arbitrary_param(ptr @.str.2, i32 %2, i32 %3, i32 %8, i32 %9, i32 %11, i32 %12, i32 %val)
+  %13 = call i32 (...) @func_taking_arbitrary_param(ptr @.str.2, i32 %2, i32 %3, i32 %11, i32 %12)
   ret void
 }
 
 define i32 @unprofiled_func() {
-  %a = load i32, ptr @data_with_unknown_hotness
   %b = load i32, ptr @external_hot_data
   %c = load i32, ptr @hot_bss
-  %ret = call i32 (...) @func_taking_arbitrary_param(i32 %a, i32 %b, i32 %c)
+  %ret = call i32 (...) @func_taking_arbitrary_param(i32 %b, i32 %c)
   ret i32 %ret
 }
 
 define void @hot_func(i32 %0) !prof !14 {
   %2 = call i32 (...) @func_taking_arbitrary_param(ptr @.str)
   %3 = srem i32 %0, 2
   %4 = sext i32 %3 to i64
-  %5 = getelementptr inbounds [2 x ptr], ptr @hot_relro_array, i64 0, i64 %4
+  %5 = getelementptr inbounds [2 x ptr], ptr @relro_var, i64 0, i64 %4
   %6 = load ptr, ptr %5
   %7 = load i32, ptr %6
   %8 = load i32, ptr @external_hot_data
@@ -166,4 +129,3 @@ attributes #0 = {"data-section"="bar"}
 !16 = !{!"branch_weights", i32 1, i32 99999}
 !17 = !{!"section_prefix", !"hot"}
 !18 = !{!"section_prefix", !"unlikely"}
-