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Actually check memcpy lengths, instead of just commenting about

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how they should be checked.

llvm-svn: 123999
This commit is contained in:
Dan Gohman 2011-01-21 22:07:57 +00:00
parent c20beed917
commit a9724ada65
2 changed files with 32 additions and 2 deletions
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6
lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -690,8 +690,10 @@ bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep,
// Second, the length of the memcpy's must be the same, or the preceeding one
// must be larger than the following one.
ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength());
if (!C1) return false;
ConstantInt *MDepLen = dyn_cast<ConstantInt>(MDep->getLength());
ConstantInt *MLen = dyn_cast<ConstantInt>(M->getLength());
if (!MDepLen || !MLen || MDepLen->getZExtValue() < MLen->getZExtValue())
return false;
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();

28
test/Transforms/MemCpyOpt/smaller.ll Normal file
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@ -0,0 +1,28 @@
; RUN: opt -memcpyopt -S < %s | FileCheck %s
; rdar://8875553
; Memcpyopt shouldn't optimize the second memcpy using the first
; because the first has a smaller size.
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp, i8* getelementptr inbounds (%struct.s* @cell, i32 0, i32 0, i32 0), i32 16, i32 4, i1 false)
target datalayout = "e-p:32:32:32"
%struct.s = type { [11 x i8], i32 }
@.str = private constant [11 x i8] c"0123456789\00"
@cell = external global %struct.s
declare void @check(%struct.s* byval %p) nounwind
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
define void @foo() nounwind {
entry:
%agg.tmp = alloca %struct.s, align 4
store i32 99, i32* getelementptr inbounds (%struct.s* @cell, i32 0, i32 1), align 4
call void @llvm.memcpy.p0i8.p0i8.i32(i8* getelementptr inbounds (%struct.s* @cell, i32 0, i32 0, i32 0), i8* getelementptr inbounds ([11 x i8]* @.str, i32 0, i32 0), i32 11, i32 1, i1 false)
%tmp = getelementptr inbounds %struct.s* %agg.tmp, i32 0, i32 0, i32 0
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %tmp, i8* getelementptr inbounds (%struct.s* @cell, i32 0, i32 0, i32 0), i32 16, i32 4, i1 false)
call void @check(%struct.s* byval %agg.tmp)
ret void
}