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fix PR8753, eliminating a case where we'd infinitely make a

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substitution because it doesn't actually change the IR.  Patch by
Jakub Staszak!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121361 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-12-09 07:39:50 +00:00
parent d8c0536651
commit f7f35467a9
2 changed files with 24 additions and 3 deletions
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8
lib/Transforms/Scalar/MemCpyOptimizer.cpp
View File

@ -675,6 +675,14 @@ bool MemCpyOpt::processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep,
if (M->getSource() != MDep->getDest() || MDep->isVolatile())
return false;
// If dep instruction is reading from our current input, then it is a noop
// transfer and substituting the input won't change this instruction. Just
// ignore the input and let someone else zap MDep. This handles cases like:
// memcpy(a <- a)
// memcpy(b <- a)
if (M->getSource() == MDep->getSource())
return false;
// 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());

19
test/Transforms/MemCpyOpt/crash.ll
View File

@ -1,5 +1,4 @@
; RUN: opt < %s -memcpyopt -disable-output
; PR4882
; RUN: opt < %s -basicaa -memcpyopt -disable-output
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
target triple = "armv7-eabi"
@ -7,7 +6,8 @@ target triple = "armv7-eabi"
%struct.qw = type { [4 x float] }
%struct.bar = type { %struct.qw, %struct.qw, %struct.qw, %struct.qw, %struct.qw, float, float}
define arm_aapcs_vfpcc void @test1(%struct.bar* %this) {
; PR4882
define void @test1(%struct.bar* %this) {
entry:
%0 = getelementptr inbounds %struct.bar* %this, i32 0, i32 0, i32 0, i32 0
store float 0.000000e+00, float* %0, align 4
@ -43,3 +43,16 @@ entry:
store float 0.000000e+00, float* %15, align 4
unreachable
}
; PR8753
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32,
i1) nounwind
define void @test2(i32 %cmd) nounwind {
call void @llvm.memcpy.p0i8.p0i8.i64(i8* undef, i8* undef, i64 20, i32 1, i1
false) nounwind
call void @llvm.memcpy.p0i8.p0i8.i64(i8* null, i8* undef, i64 20, i32 1, i1
false) nounwind
ret void
}