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fix infinite loop in instcombine with more than 4GB memcpy

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- memcpy size is wrongly truncated into 32-bit and treat 8GB memcpy is
  0-sized memcpy
- as 0-sized memcpy/memset is already removed before SimplifyMemTransfer
  and SimplifyMemSet in visitCallInst, replace 0 checking with
  assertions.
- replace getZExtValue() with getLimitedValue() according to
  Eli Friedman



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161923 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Liao 2012-08-15 03:49:59 +00:00
parent c2de3ddb23
commit 9441ad0b6e
2 changed files with 12 additions and 6 deletions
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10
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -51,8 +51,8 @@ Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
// if the size is something we can handle with a single primitive load/store.
// A single load+store correctly handles overlapping memory in the memmove
// case.
unsigned Size = MemOpLength->getZExtValue();
if (Size == 0) return MI; // Delete this mem transfer.
uint64_t Size = MemOpLength->getLimitedValue();
assert(Size && "0-sized memory transfering should be removed already.");
if (Size > 8 || (Size&(Size-1)))
return 0; // If not 1/2/4/8 bytes, exit.
@ -133,11 +133,9 @@ Instruction *InstCombiner::SimplifyMemSet(MemSetInst *MI) {
ConstantInt *FillC = dyn_cast<ConstantInt>(MI->getValue());
if (!LenC || !FillC || !FillC->getType()->isIntegerTy(8))
return 0;
uint64_t Len = LenC->getZExtValue();
uint64_t Len = LenC->getLimitedValue();
Alignment = MI->getAlignment();
// If the length is zero, this is a no-op
if (Len == 0) return MI; // memset(d,c,0,a) -> noop
assert(Len && "0-sized memory setting should be removed already.");
// memset(s,c,n) -> store s, c (for n=1,2,4,8)
if (Len <= 8 && isPowerOf2_32((uint32_t)Len)) {

8
test/Transforms/InstCombine/memcpy.ll
View File

@ -1,6 +1,7 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
define void @test1(i8* %a) {
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 false)
@ -17,3 +18,10 @@ define void @test2(i8* %a) {
; CHECK: define void @test2
; CHECK-NEXT: call void @llvm.memcpy
}
define void @test3(i8* %d, i8* %s) {
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %d, i8* %s, i64 17179869184, i32 4, i1 false)
ret void
; CHECK: define void @test3
; CHECK-NEXT: call void @llvm.memcpy
}