Reland r262337 "calculate builtin_object_size if arg is a removable pointer"
Original commit message:
calculate builtin_object_size if argument is a removable pointer
This patch fixes calculating correct value for builtin_object_size function
when pointer is used only in builtin_object_size function call and never
after that.
Patch by Strahinja Petrovic.
Differential Revision: http://reviews.llvm.org/D17337
Reland the original change with a small modification (first do a null check
and then do the cast) to satisfy ubsan.
llvm-svn: 263011
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index f25f063..af8d569 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1942,8 +1942,31 @@
SmallVector<WeakVH, 64> Users;
if (isAllocSiteRemovable(&MI, Users, TLI)) {
for (unsigned i = 0, e = Users.size(); i != e; ++i) {
- Instruction *I = cast_or_null<Instruction>(&*Users[i]);
- if (!I) continue;
+ // Lowering all @llvm.objectsize calls first because they may
+ // use a bitcast/GEP of the alloca we are removing.
+ if (!Users[i])
+ continue;
+
+ Instruction *I = cast<Instruction>(&*Users[i]);
+
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ if (II->getIntrinsicID() == Intrinsic::objectsize) {
+ uint64_t Size;
+ if (!getObjectSize(II->getArgOperand(0), Size, DL, TLI)) {
+ ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
+ Size = CI->isZero() ? -1ULL : 0;
+ }
+ replaceInstUsesWith(*I, ConstantInt::get(I->getType(), Size));
+ eraseInstFromFunction(*I);
+ Users[i] = nullptr; // Skip examining in the next loop.
+ }
+ }
+ }
+ for (unsigned i = 0, e = Users.size(); i != e; ++i) {
+ if (!Users[i])
+ continue;
+
+ Instruction *I = cast<Instruction>(&*Users[i]);
if (ICmpInst *C = dyn_cast<ICmpInst>(I)) {
replaceInstUsesWith(*C,
@@ -1951,12 +1974,6 @@
C->isFalseWhenEqual()));
} else if (isa<BitCastInst>(I) || isa<GetElementPtrInst>(I)) {
replaceInstUsesWith(*I, UndefValue::get(I->getType()));
- } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
- if (II->getIntrinsicID() == Intrinsic::objectsize) {
- ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
- uint64_t DontKnow = CI->isZero() ? -1ULL : 0;
- replaceInstUsesWith(*I, ConstantInt::get(I->getType(), DontKnow));
- }
}
eraseInstFromFunction(*I);
}