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[LoopUnroll] Use undef for phis with no value live 

We would create a phi node with a zero initialized operand instead of
undef in the case where no value was originally available.  This was
problematic for x86_mmx which has no null value.

llvm-svn: 241143
This commit is contained in:
David Majnemer 2015-07-01 05:38:07 +00:00
parent 9402e27ae0
commit 453f7a1480
2 changed files with 25 additions and 1 deletions
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2
llvm/lib/Transforms/Utils/LoopUnrollRuntime.cpp
View File

@ -86,7 +86,7 @@ static void ConnectProlog(Loop *L, Value *BECount, unsigned Count,
if (L->contains(PN)) {
NewPN->addIncoming(PN->getIncomingValueForBlock(NewPH), OrigPH);
} else {
NewPN->addIncoming(Constant::getNullValue(PN->getType()), OrigPH);
NewPN->addIncoming(UndefValue::get(PN->getType()), OrigPH);
}
Value *V = PN->getIncomingValueForBlock(Latch);

24
llvm/test/Transforms/LoopUnroll/X86/mmx.ll Normal file
View File

@ -0,0 +1,24 @@
; RUN: opt < %s -S -loop-unroll | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define x86_mmx @f() #0 {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%phi = phi i32 [ 1, %entry ], [ %add, %for.body ]
%add = add i32 %phi, 1
%cmp = icmp eq i32 %phi, 0
br i1 %cmp, label %exit, label %for.body
exit: ; preds = %for.body
%ret = phi x86_mmx [ undef, %for.body ]
; CHECK: %[[ret_unr:.*]] = phi x86_mmx [ undef,
; CHECK: %[[ret_ph:.*]] = phi x86_mmx [ undef,
; CHECK: %[[ret:.*]] = phi x86_mmx [ %[[ret_unr]], {{.*}} ], [ %[[ret_ph]]
; CHECK: ret x86_mmx %[[ret]]
ret x86_mmx %ret
}
attributes #0 = { "target-cpu"="x86-64" }