teach DSE and isInstructionTriviallyDead() about calloc

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156553 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 3 deletions

diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp
index c8c5360..a46e802 100644
--- a/lib/Transforms/Scalar/DeadStoreElimination.cpp
+++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp
@@ -282,6 +282,12 @@ static uint64_t getPointerSize(const Value *V, AliasAnalysis &AA) {
       return C->getZExtValue();
   }
 
+  if (const CallInst *CI = extractCallocCall(V)) {
+    if (const ConstantInt *C1 = dyn_cast<ConstantInt>(CI->getArgOperand(0)))
+      if (const ConstantInt *C2 = dyn_cast<ConstantInt>(CI->getArgOperand(1)))
+       return (C1->getValue() * C2->getValue()).getZExtValue();
+  }
+
   if (TD == 0)
     return AliasAnalysis::UnknownSize;
 
@@ -704,9 +710,11 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
 
     // Okay, so these are dead heap objects, but if the pointer never escapes
     // then it's leaked by this function anyways.
-    if (CallInst *CI = extractMallocCall(I))
-      if (!PointerMayBeCaptured(CI, true, true))
-        DeadStackObjects.insert(CI);
+    CallInst *CI = extractMallocCall(I);
+    if (!CI)
+      CI = extractCallocCall(I);
+    if (CI && !PointerMayBeCaptured(CI, true, true))
+      DeadStackObjects.insert(CI);
   }
 
   // Treat byval arguments the same, stores to them are dead at the end of the
@@ -759,6 +767,11 @@ bool DSE::handleEndBlock(BasicBlock &BB) {
       continue;
     }
 
+    if (CallInst *CI = extractCallocCall(BBI)) {
+      DeadStackObjects.erase(CI);
+      continue;
+    }
+
     if (CallSite CS = cast<Value>(BBI)) {
       // If this call does not access memory, it can't be loading any of our
       // pointers.