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GVN: Preserve invariant.load metadata 

If both instructions to be replaced are marked invariant the resulting
instruction is invariant.

rdar://13358910

Fix by Erik Eckstein!

llvm-svn: 211801
This commit is contained in:
Arnold Schwaighofer 2014-06-26 19:51:19 +00:00
parent 83e0723457
commit ed988fb97d
2 changed files with 34 additions and 0 deletions
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4
llvm/lib/Transforms/Scalar/GVN.cpp
View File

@ -1798,6 +1798,10 @@ static void patchReplacementInstruction(Instruction *I, Value *Repl) {
case LLVMContext::MD_fpmath:
ReplInst->setMetadata(Kind, MDNode::getMostGenericFPMath(IMD, ReplMD));
break;
case LLVMContext::MD_invariant_load:
// Only set the !invariant.load if it is present in both instructions.
ReplInst->setMetadata(Kind, IMD);
break;
}
}
}

30
llvm/test/Transforms/GVN/invariant-load.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt -basicaa -gvn -S < %s | FileCheck %s
define i32 @test1(i32* nocapture %p, i8* nocapture %q) {
; CHECK-LABEL: test1
; CHECK: %x = load i32* %p, align 4, !invariant.load !0
; CHECK-NOT: %y = load
entry:
%x = load i32* %p, align 4, !invariant.load !0
%conv = trunc i32 %x to i8
store i8 %conv, i8* %q, align 1
%y = load i32* %p, align 4, !invariant.load !0
%add = add i32 %y, 1
ret i32 %add
}
define i32 @test2(i32* nocapture %p, i8* nocapture %q) {
; CHECK-LABEL: test2
; CHECK-NOT: !invariant.load
; CHECK-NOT: %y = load
entry:
%x = load i32* %p, align 4
%conv = trunc i32 %x to i8
store i8 %conv, i8* %q, align 1
%y = load i32* %p, align 4, !invariant.load !0
%add = add i32 %y, 1
ret i32 %add
}
!0 = metadata !{ }