[ThinLTO] Ensure the TargetLibraryInfo is constructed early enough

Summary:
Without this change, the WholeProgramDevirt pass, which requires the
TargetLibraryInfo, will construct one from the default triple.

Fixes PR38139.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, steven_wu, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D49278

llvm-svn: 337750

llvm/lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -903,6 +903,8 @@ void PassManagerBuilder::addLateLTOOptimizationPasses(
 void PassManagerBuilder::populateThinLTOPassManager(
     legacy::PassManagerBase &PM) {
   PerformThinLTO = true;
+  if (LibraryInfo)
+    PM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
 
   if (VerifyInput)
     PM.add(createVerifierPass());

llvm/test/LTO/X86/triple-init.ll

+; Test to ensure that the LTO pipelines add pass to build the TargetLibraryInfo
+; using the specified target triple.
+
+; Check with regular LTO
 ; RUN: llvm-as < %s >%t1
 ; RUN: llvm-lto -exported-symbol=_main  -o %t2 %t1
-; RUN: llvm-nm %t2 | FileCheck %s 
+; RUN: llvm-nm %t2 | FileCheck %s
+; Check with ThinLTO. Use llvm-lto2 since this adds earlier passes requiring
+; the TargetLibraryInfo with ThinLTO (WholeProgramDevirt).
+; RUN: opt -module-summary -o %t1 %s
+; RUN: llvm-lto2 run -r %t1,_pow, -r %t1,_main,plx -o %t2 %t1
+; RUN: llvm-nm %t2.1 | FileCheck %s
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.9"

llvm/test/LTO/X86/triple-init2.ll

+; Test to ensure that the LTO pipelines add pass to build the TargetLibraryInfo
+; using the specified target triple.
+
+; Check with regular LTO
+; RUN: llvm-as < %s >%t1
+; RUN: llvm-lto -exported-symbol=main -o %t2 %t1
+; RUN: llvm-nm %t2 | FileCheck %s
+; Check with ThinLTO. Use llvm-lto2 since this adds earlier passes requiring
+; the TargetLibraryInfo with ThinLTO (WholeProgramDevirt).
+; RUN: opt -module-summary -o %t1 %s
+; RUN: llvm-lto2 run -r %t1,main,plx -o %t2 %t1
+; RUN: llvm-nm %t2.1 | FileCheck %s
+
+; We check that LTO will be aware of target triple and prevent exp2 to ldexpf
+; transformation on Windows.
+; CHECK: U exp2f
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.11.0"
+
+define dso_local i32 @main(i32 %argc, i8** nocapture readnone %argv) local_unnamed_addr {
+entry:
+  %conv = sitofp i32 %argc to float
+  %exp2 = tail call float @llvm.exp2.f32(float %conv)
+  %conv1 = fptosi float %exp2 to i32
+  ret i32 %conv1
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare float @llvm.exp2.f32(float)
+