[MergeICmps] Don't crash when memcmp is not available

Fixes clang crashing with -fno-builtin, PR37527.

llvm-svn: 332808

2 files changed, 46 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Scalar/MergeICmps.cpp b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
index 57dd2292dfb..ff0183a8ea2 100644
--- a/llvm/lib/Transforms/Scalar/MergeICmps.cpp
+++ b/llvm/lib/Transforms/Scalar/MergeICmps.cpp
@@ -768,6 +768,10 @@ PreservedAnalyses MergeICmps::runImpl(Function &F, const TargetLibraryInfo *TLI,
   // The rationale is to avoid turning small chains into memcmp calls.
   if (!TTI->enableMemCmpExpansion(true)) return PreservedAnalyses::all();
 
+  // If we don't have memcmp avaiable we can't emit calls to it.
+  if (!TLI->has(LibFunc_memcmp))
+    return PreservedAnalyses::all();
+
   bool MadeChange = false;
 
   for (auto BBIt = ++F.begin(); BBIt != F.end(); ++BBIt) {
diff --git a/llvm/test/Transforms/MergeICmps/X86/pair-int32-int32.ll b/llvm/test/Transforms/MergeICmps/X86/pair-int32-int32.ll
index fb7976d3b32..37201fa3956 100644
--- a/llvm/test/Transforms/MergeICmps/X86/pair-int32-int32.ll
+++ b/llvm/test/Transforms/MergeICmps/X86/pair-int32-int32.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S | FileCheck %s --check-prefix=X86
+; RUN: opt < %s -mergeicmps -mtriple=x86_64-unknown-unknown -S -disable-simplify-libcalls | FileCheck %s --check-prefix=X86-NOBUILTIN
 
 %"struct.std::pair" = type { i32, i32 }
 
@@ -17,6 +18,25 @@ define zeroext i1 @opeq1(
 ; X86-NEXT:    [[TMP1:%.*]] = phi i1 [ [[TMP0]], [[ENTRY:%.*]] ]
 ; X86-NEXT:    ret i1 [[TMP1]]
 ;
+; X86-NOBUILTIN-LABEL: @opeq1(
+; X86-NOBUILTIN-NEXT:  entry:
+; X86-NOBUILTIN-NEXT:    [[FIRST_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A:%.*]], i64 0, i32 0
+; X86-NOBUILTIN-NEXT:    [[TMP0:%.*]] = load i32, i32* [[FIRST_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[FIRST1_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B:%.*]], i64 0, i32 0
+; X86-NOBUILTIN-NEXT:    [[TMP1:%.*]] = load i32, i32* [[FIRST1_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[CMP_I:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
+; X86-NOBUILTIN-NEXT:    br i1 [[CMP_I]], label [[LAND_RHS_I:%.*]], label [[OPEQ1_EXIT:%.*]]
+; X86-NOBUILTIN:       land.rhs.i:
+; X86-NOBUILTIN-NEXT:    [[SECOND_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A]], i64 0, i32 1
+; X86-NOBUILTIN-NEXT:    [[TMP2:%.*]] = load i32, i32* [[SECOND_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[SECOND2_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B]], i64 0, i32 1
+; X86-NOBUILTIN-NEXT:    [[TMP3:%.*]] = load i32, i32* [[SECOND2_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[CMP3_I:%.*]] = icmp eq i32 [[TMP2]], [[TMP3]]
+; X86-NOBUILTIN-NEXT:    br label [[OPEQ1_EXIT]]
+; X86-NOBUILTIN:       opeq1.exit:
+; X86-NOBUILTIN-NEXT:    [[TMP4:%.*]] = phi i1 [ false, [[ENTRY:%.*]] ], [ [[CMP3_I]], [[LAND_RHS_I]] ]
+; X86-NOBUILTIN-NEXT:    ret i1 [[TMP4]]
+;
   %"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
   %"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {
 entry:
@@ -54,11 +74,30 @@ define zeroext i1 @opeq1_inverse(
 ; X86-NEXT:    [[CSTR:%.*]] = bitcast i32* [[SECOND_I]] to i8*
 ; X86-NEXT:    [[CSTR1:%.*]] = bitcast i32* [[SECOND2_I]] to i8*
 ; X86-NEXT:    [[MEMCMP:%.*]] = call i32 @memcmp(i8* [[CSTR]], i8* [[CSTR1]], i64 8)
-; X86-NEXT:    [[TMP0:%.*]] = icmp eq i32 [[MEMCMP]], 0
+; X86-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[MEMCMP]], 0
 ; X86-NEXT:    br label [[OPEQ1_EXIT:%.*]]
 ; X86:       opeq1.exit:
-; X86-NEXT:    [[TMP1:%.*]] = phi i1 [ [[TMP0]], [[LAND_RHS_I:%.*]] ]
-; X86-NEXT:    ret i1 [[TMP1]]
+; X86-NEXT:    [[TMP2:%.*]] = phi i1 [ [[TMP1]], [[LAND_RHS_I]] ]
+; X86-NEXT:    ret i1 [[TMP2]]
+;
+; X86-NOBUILTIN-LABEL: @opeq1_inverse(
+; X86-NOBUILTIN-NEXT:  entry:
+; X86-NOBUILTIN-NEXT:    [[FIRST_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A:%.*]], i64 0, i32 1
+; X86-NOBUILTIN-NEXT:    [[TMP0:%.*]] = load i32, i32* [[FIRST_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[FIRST1_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B:%.*]], i64 0, i32 1
+; X86-NOBUILTIN-NEXT:    [[TMP1:%.*]] = load i32, i32* [[FIRST1_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[CMP_I:%.*]] = icmp eq i32 [[TMP0]], [[TMP1]]
+; X86-NOBUILTIN-NEXT:    br i1 [[CMP_I]], label [[LAND_RHS_I:%.*]], label [[OPEQ1_EXIT:%.*]]
+; X86-NOBUILTIN:       land.rhs.i:
+; X86-NOBUILTIN-NEXT:    [[SECOND_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[A]], i64 0, i32 0
+; X86-NOBUILTIN-NEXT:    [[TMP2:%.*]] = load i32, i32* [[SECOND_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[SECOND2_I:%.*]] = getelementptr inbounds %"struct.std::pair", %"struct.std::pair"* [[B]], i64 0, i32 0
+; X86-NOBUILTIN-NEXT:    [[TMP3:%.*]] = load i32, i32* [[SECOND2_I]], align 4
+; X86-NOBUILTIN-NEXT:    [[CMP3_I:%.*]] = icmp eq i32 [[TMP2]], [[TMP3]]
+; X86-NOBUILTIN-NEXT:    br label [[OPEQ1_EXIT]]
+; X86-NOBUILTIN:       opeq1.exit:
+; X86-NOBUILTIN-NEXT:    [[TMP4:%.*]] = phi i1 [ false, [[ENTRY:%.*]] ], [ [[CMP3_I]], [[LAND_RHS_I]] ]
+; X86-NOBUILTIN-NEXT:    ret i1 [[TMP4]]
 ;
   %"struct.std::pair"* nocapture readonly dereferenceable(8) %a,
   %"struct.std::pair"* nocapture readonly dereferenceable(8) %b) local_unnamed_addr #0 {