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CSE: allow PerformTrivialCoalescing to check copies across basic block

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boundaries.

Given the following case:
BB0
  %vreg1<def> = SUBrr %vreg0, %vreg7
  %vreg2<def> = COPY %vreg7
BB1
  %vreg10<def> = SUBrr %vreg0, %vreg2
We should be able to CSE between SUBrr in BB0 and SUBrr in BB1.

rdar://12462006


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168717 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Manman Ren 2012-11-27 18:58:41 +00:00
parent a241b58f8d
commit 39834da697
2 changed files with 32 additions and 2 deletions
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2
lib/CodeGen/MachineCSE.cpp
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@ -126,8 +126,6 @@ bool MachineCSE::PerformTrivialCoalescing(MachineInstr *MI,
// deleted.
continue;
MachineInstr *DefMI = MRI->getVRegDef(Reg);
if (DefMI->getParent() != MBB)
continue;
if (!DefMI->isCopy())
continue;
unsigned SrcReg = DefMI->getOperand(1).getReg();

32
test/CodeGen/ARM/machine-cse-cmp.ll
View File

@ -45,3 +45,35 @@ for.cond1.preheader: ; preds = %entry
}
declare void @llvm.memset.p0i8.i32(i8* nocapture, i8, i32, i32, i1) nounwind
; rdar://12462006
define i8* @f3(i8* %base, i32* nocapture %offset, i32 %size) nounwind {
entry:
; CHECK: f3:
; CHECK-NOT: sub
; CHECK: cmp
; CHECK: blt
%0 = load i32* %offset, align 4
%cmp = icmp slt i32 %0, %size
%s = sub nsw i32 %0, %size
%size2 = sub nsw i32 %size, 0
br i1 %cmp, label %return, label %if.end
if.end:
; We are checking cse between %sub here and %s in entry block.
%sub = sub nsw i32 %0, %size2
%s2 = sub nsw i32 %s, %size
%s3 = sub nsw i32 %sub, %s2
; CHECK: sub [[R1:r[0-9]+]], [[R2:r[0-9]+]], r2
; CHECK: sub [[R3:r[0-9]+]], [[R1]], r2
; CHECK: sub [[R4:r[0-9]+]], [[R1]], [[R3]]
; CHECK-NOT: sub
; CHECK: str
store i32 %s3, i32* %offset, align 4
%add.ptr = getelementptr inbounds i8* %base, i32 %sub
br label %return
return:
%retval.0 = phi i8* [ %add.ptr, %if.end ], [ null, %entry ]
ret i8* %retval.0
}