[asan] Don't run stack malloc on functions containing inline assembly.

It makes LLVM run out of registers even on 64-bit platforms. For example, the
following test case fails on darwin.

clang -cc1 -O0 -triple x86_64-apple-macosx10.10.0 -emit-obj -fsanitize=address -mstackrealign -o ~/tmp/ex.o -x c ex.c
error: inline assembly requires more registers than available

void TestInlineAssembly(const unsigned char *S, unsigned int pS, unsigned char *D, unsigned int pD, unsigned int h) {

unsigned int sr = 4, pDiffD = pD - 5;
unsigned int pDiffS = (pS << 1) - 5;
char flagSA = ((pS & 15) == 0),
flagDA = ((pD & 15) == 0);
asm volatile (
  "mov %0,  %%"PTR_REG("si")"\n"
  "mov %2,  %%"PTR_REG("cx")"\n"
  "mov %1,  %%"PTR_REG("di")"\n"
  "mov %8,  %%"PTR_REG("ax")"\n"
  :
  : "m" (S), "m" (D), "m" (pS), "m" (pDiffS), "m" (pDiffD), "m" (sr), "m" (flagSA), "m" (flagDA), "m" (h)
  : "%"PTR_REG("si"), "%"PTR_REG("di"), "%"PTR_REG("ax"), "%"PTR_REG("cx"), "%"PTR_REG("dx"), "memory"
);
}

http://reviews.llvm.org/D10719

llvm-svn: 240722

1 files changed, 3 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 2dd2fe6211c..ff4368198be 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -1753,11 +1753,10 @@ void FunctionStackPoisoner::poisonStack() {
   uint64_t LocalStackSize = L.FrameSize;
   bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
                        LocalStackSize <= kMaxStackMallocSize;
-  // Don't do dynamic alloca in presence of inline asm: too often it makes
-  // assumptions on which registers are available. Don't do stack malloc in the
-  // presence of inline asm on 32-bit platforms for the same reason.
+  // Don't do dynamic alloca or stack malloc in presence of inline asm:
+  // too often it makes assumptions on which registers are available.
   bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
-  DoStackMalloc &= !HasNonEmptyInlineAsm || ASan.LongSize != 32;
+  DoStackMalloc &= !HasNonEmptyInlineAsm;
 
   Value *StaticAlloca =
       DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);