PNaCl ABI: Strip alignment info from memcpy/memmove/memset intrinsic calls

Do the same for memcpy/memmove/memset intrinsic calls that we have
already done for integer loads and stores: Remove assumptions about
pointer alignment by setting the alignment argument to 1.  Make the
ABI checker require this.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3445
TEST=*.ll tests + PNaCl toolchain trybots

Review URL: https://codereview.chromium.org/17563008

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/Analysis/NaCl/PNaClABIVerifyFunctions.cpp b/lib/Analysis/NaCl/PNaClABIVerifyFunctions.cpp
index 1fe79757a0..9a96d19ed4 100644
--- a/lib/Analysis/NaCl/PNaClABIVerifyFunctions.cpp
+++ b/lib/Analysis/NaCl/PNaClABIVerifyFunctions.cpp
@@ -315,6 +315,18 @@ const char *PNaClABIVerifyFunctions::checkInstruction(const Instruction *Inst) {
                 isa<MDNode>(Arg)))
             return "bad intrinsic operand";
         }
+        // Disallow alignments other than 1 on memcpy() etc., for the
+        // same reason that we disallow them on integer loads and
+        // stores.
+        if (const MemIntrinsic *MemOp = dyn_cast<MemIntrinsic>(Call)) {
+          // Avoid the getAlignment() method here because it aborts if
+          // the alignment argument is not a Constant.
+          Value *AlignArg = MemOp->getArgOperand(3);
+          if (!isa<ConstantInt>(AlignArg) ||
+              cast<ConstantInt>(AlignArg)->getZExtValue() != 1) {
+            return "bad alignment";
+          }
+        }
         // Allow the instruction and skip the later checks.
         return NULL;
       }