From: Michael Liao <michael.liao@intel.com>
Date: Wed, 15 Aug 2012 03:49:59 +0000 (+0000)
Subject: fix infinite loop in instcombine with more than 4GB memcpy
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9441ad0b6e02ee9558168b37a9620ef1afe79388;hp=c2de3ddb23e45859f8b4ffdc21f796dc39703280;p=oota-llvm.git

fix infinite loop in instcombine with more than 4GB memcpy

- 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
---

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index d34fab103fa..cbe1ca4ddce 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -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)) {
diff --git a/test/Transforms/InstCombine/memcpy.ll b/test/Transforms/InstCombine/memcpy.ll
index 8a2e3aaad02..3a68ff95af8 100644
--- a/test/Transforms/InstCombine/memcpy.ll
+++ b/test/Transforms/InstCombine/memcpy.ll
@@ -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
+}