ThinLTO: Fix inline assembly references to static functions with CFI

Create an internal alias with the original name for static functions
that are renamed in promoteInternals to avoid breaking inline
assembly references to them.

Relands 700d07f with -msvc targets
fixed.

Link: ClangBuiltLinux/linux#1354

Reviewed By: nickdesaulniers, pcc

Differential Revision: https://reviews.llvm.org/D104058

(cherry picked from commit 7ce1c4d)

Author: samitolvanen

llvm/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp

@@ -33,6 +33,19 @@ using namespace llvm;
 
 namespace {
 
+// Determine if a promotion alias should be created for a symbol name.
+static bool allowPromotionAlias(const std::string &Name) {
+  // Promotion aliases are used only in inline assembly. It's safe to
+  // simply skip unusual names. Subset of MCAsmInfo::isAcceptableChar()
+  // and MCAsmInfoXCOFF::isAcceptableChar().
+  for (const char &C : Name) {
+    if (isAlnum(C) || C == '_' || C == '.')
+      continue;
+    return false;
+  }
+  return true;
+}
+
 // Promote each local-linkage entity defined by ExportM and used by ImportM by
 // changing visibility and appending the given ModuleId.
 void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
@@ -55,6 +68,7 @@ void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
       }
     }
 
+    std::string OldName = Name.str();
     std::string NewName = (Name + ModuleId).str();
 
     if (const auto *C = ExportGV.getComdat())
@@ -69,6 +83,13 @@ void promoteInternals(Module &ExportM, Module &ImportM, StringRef ModuleId,
       ImportGV->setName(NewName);
       ImportGV->setVisibility(GlobalValue::HiddenVisibility);
     }
+
+    if (isa<Function>(&ExportGV) && allowPromotionAlias(OldName)) {
+      // Create a local alias with the original name to avoid breaking
+      // references from inline assembly.
+      std::string Alias = ".set " + OldName + "," + NewName + "\n";
+      ExportM.appendModuleInlineAsm(Alias);
+    }
   }
 
   if (!RenamedComdats.empty())

llvm/test/ThinLTO/X86/devirt2.ll

@@ -131,10 +131,12 @@
 ; RUN:   -r=%t1.o,_ZN1D1mEi, \
 ; RUN:   -r=%t1.o,test2, \
 ; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1A1nEi, \
 ; RUN:   -r=%t2.o,_ZN1B1fEi,p \
 ; RUN:   -r=%t2.o,_ZN1C1fEi,p \
 ; RUN:   -r=%t2.o,_ZN1D1mEi,p \
 ; RUN:   -r=%t2.o,_ZN1E1mEi,p \
+; RUN:   -r=%t2.o,_ZN1E1mEi, \
 ; RUN:   -r=%t2.o,_ZTV1B, \
 ; RUN:   -r=%t2.o,_ZTV1C, \
 ; RUN:   -r=%t2.o,_ZTV1D, \
@@ -167,10 +169,12 @@
 ; RUN:   -r=%t1.o,_ZN1D1mEi, \
 ; RUN:   -r=%t1.o,test2, \
 ; RUN:   -r=%t2.o,_ZN1A1nEi,p \
+; RUN:   -r=%t2.o,_ZN1A1nEi, \
 ; RUN:   -r=%t2.o,_ZN1B1fEi,p \
 ; RUN:   -r=%t2.o,_ZN1C1fEi,p \
 ; RUN:   -r=%t2.o,_ZN1D1mEi,p \
 ; RUN:   -r=%t2.o,_ZN1E1mEi,p \
+; RUN:   -r=%t2.o,_ZN1E1mEi, \
 ; RUN:   -r=%t2.o,_ZTV1B, \
 ; RUN:   -r=%t2.o,_ZTV1C, \
 ; RUN:   -r=%t2.o,_ZTV1D, \

llvm/test/Transforms/ThinLTOBitcodeWriter/cfi-icall-static-inline-asm.ll

@@ -0,0 +1,22 @@
+; REQUIRES: x86-registered-target
+; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o - %s | llvm-modextract -b -n 0 -o - | llvm-dis | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK: module asm ".set a,a.[[HASH:[0-9a-f]+]]"
+
+define void @b() {
+  %f = alloca void ()*, align 8
+  ; CHECK: store{{.*}} @a.[[HASH]],{{.*}} %f
+  store void ()* @a, void ()** %f, align 8
+  ; CHECK: %1 = call void ()* asm sideeffect "leaq a(%rip)
+  %1 = call void ()* asm sideeffect "leaq a(%rip), $0\0A\09", "=r,~{dirflag},~{fpsr},~{flags}"()
+  ret void
+}
+
+; CHECK: define{{.*}} @a.[[HASH]](){{.*}} !type
+define internal void @a() !type !0 {
+  ret void
+}
+
+!0 = !{i64 0, !"typeid1"}

llvm/test/Transforms/ThinLTOBitcodeWriter/split-internal2.ll

@@ -1,3 +1,4 @@
+; REQUIRES: x86-registered-target
 ; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o %t0 %t
 ; RUN: llvm-modextract -b -n 1 -o %t1 %t
@@ -7,6 +8,8 @@
 ; RUN: llvm-bcanalyzer -dump %t0 | FileCheck --check-prefix=BCA0 %s
 ; RUN: llvm-bcanalyzer -dump %t1 | FileCheck --check-prefix=BCA1 %s
 
+target triple = "x86_64-unknown-linux-gnu"
+
 ; ERROR: llvm-modextract: error: module index out of range; bitcode file contains 2 module(s)
 
 ; BCA0: <GLOBALVAL_SUMMARY_BLOCK

llvm/test/Transforms/ThinLTOBitcodeWriter/split-vfunc-internal.ll

@@ -1,7 +1,10 @@
+; REQUIRES: x86-registered-target
 ; RUN: opt -thinlto-bc -thinlto-split-lto-unit -o %t %s
 ; RUN: llvm-modextract -b -n 0 -o - %t | llvm-dis | FileCheck --check-prefix=M0 %s
 ; RUN: llvm-modextract -b -n 1 -o - %t | llvm-dis | FileCheck --check-prefix=M1 %s
 
+target triple = "x86_64-unknown-linux-gnu"
+
 define [1 x i8*]* @source() {
   ret [1 x i8*]* @g
 }