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Don't eliminate memcpy's when the address of the pointer may itself be relevant. Fixes PR18304. Patch by David Wiberg!

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212970 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2014-07-14 18:52:02 +00:00
parent e31c05926b
commit bd5603c16e
7 changed files with 35 additions and 7 deletions
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6
lib/Transforms/Scalar/MemCpyOptimizer.cpp
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@ -684,6 +684,12 @@ bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy,
}
}
// Check that src isn't captured by the called function since the
// transformation can cause aliasing issues in that case.
for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
if (CS.getArgument(i) == cpySrc && !CS.doesNotCapture(i))
return false;
// Since we're changing the parameter to the callsite, we need to make sure
// that what would be the new parameter dominates the callsite.
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();

4
test/Transforms/MemCpyOpt/2008-02-24-MultipleUseofSRet.ll
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@ -6,7 +6,7 @@ target triple = "i386-pc-linux-gnu"
%0 = type { x86_fp80, x86_fp80 }
define internal fastcc void @initialize(%0* noalias sret %agg.result) nounwind {
define internal fastcc void @initialize(%0* noalias nocapture sret %agg.result) nounwind {
entry:
%agg.result.03 = getelementptr %0* %agg.result, i32 0, i32 0
store x86_fp80 0xK00000000000000000000, x86_fp80* %agg.result.03
@ -15,7 +15,7 @@ entry:
ret void
}
declare fastcc x86_fp80 @passed_uninitialized(%0*) nounwind
declare fastcc x86_fp80 @passed_uninitialized(%0* nocapture) nounwind
define fastcc void @badly_optimized() nounwind {
entry:

2
test/Transforms/MemCpyOpt/2008-03-13-ReturnSlotBitcast.ll
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@ -4,7 +4,7 @@ target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f3
%a = type { i32 }
%b = type { float }
declare void @g(%a*)
declare void @g(%a* nocapture)
define float @f() {
entry:

22
test/Transforms/MemCpyOpt/capturing-func.ll Normal file
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@ -0,0 +1,22 @@
; RUN: opt < %s -basicaa -memcpyopt -S | FileCheck %s
target datalayout = "e"
declare void @foo(i8*)
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
define void @test() {
%ptr1 = alloca i8
%ptr2 = alloca i8
call void @foo(i8* %ptr2)
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %ptr1, i8* %ptr2, i32 1, i32 1, i1 false)
call void @foo(i8* %ptr1)
ret void
; Check that the transformation isn't applied if the called function can
; capture the pointer argument (i.e. the nocapture attribute isn't present)
; CHECK-LABEL: @test(
; CHECK: call void @foo(i8* %ptr2)
; CHECK-NEXT: call void @llvm.memcpy
; CHECK-NEXT: call void @foo(i8* %ptr1)
}

2
test/Transforms/MemCpyOpt/loadstore-sret.ll
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@ -22,4 +22,4 @@ _ZNSt8auto_ptrIiED1Ev.exit:
ret void
}
declare void @_Z3barv(%"class.std::auto_ptr"* sret)
declare void @_Z3barv(%"class.std::auto_ptr"* nocapture sret)

4
test/Transforms/MemCpyOpt/memcpy.ll
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@ -29,7 +29,7 @@ entry:
; CHECK: ret void
}
declare void @ccoshl(%0* sret , x86_fp80, x86_fp80) nounwind
declare void @ccoshl(%0* nocapture sret, x86_fp80, x86_fp80) nounwind
; The intermediate alloca and one of the memcpy's should be eliminated, the
@ -202,7 +202,7 @@ define void @test10(%opaque* noalias nocapture sret %x, i32 %y) {
ret void
}
declare void @f1(%struct.big* sret)
declare void @f1(%struct.big* nocapture sret)
declare void @f2(%struct.big*)
; CHECK: attributes [[NUW]] = { nounwind }

2
test/Transforms/MemCpyOpt/sret.ll
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@ -25,6 +25,6 @@ entry:
ret void
}
declare void @ccoshl(%0* noalias sret, %0* byval) nounwind
declare void @ccoshl(%0* noalias nocapture sret, %0* byval) nounwind
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind