diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCalls.cpp | 46 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/objsize.ll | 30 |
2 files changed, 66 insertions, 10 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp index 47c37c4658..f06cd12ffc 100644 --- a/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -633,16 +633,42 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { break; } case Intrinsic::objectsize: { - ConstantInt *Const = cast<ConstantInt>(II->getOperand(2)); - const Type *Ty = CI.getType(); - - // 0 is maximum number of bytes left, 1 is minimum number of bytes left. - // TODO: actually add these values, the current return values are "don't - // know". - if (Const->getZExtValue() == 0) - return ReplaceInstUsesWith(CI, Constant::getAllOnesValue(Ty)); - else - return ReplaceInstUsesWith(CI, ConstantInt::get(Ty, 0)); + const Type *ReturnTy = CI.getType(); + Value *Op1 = II->getOperand(1); + + // If we're a constant expr then we just return the number of bytes + // left in whatever we're indexing. Since it's constant there's no + // need for maximum or minimum bytes. + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) { + // If this isn't a GEP give up. + if (CE->getOpcode() != Instruction::GetElementPtr) return 0; + + const PointerType *ObjTy = + reinterpret_cast<const PointerType*>(CE->getOperand(0)->getType()); + + if (const ArrayType *AT = dyn_cast<ArrayType>(ObjTy->getElementType())) { + + // Deal with multi-dimensional arrays + const ArrayType *SAT = AT; + while ((AT = dyn_cast<ArrayType>(AT->getElementType()))) + SAT = AT; + + size_t numElems = SAT->getNumElements(); + // We return the remaining bytes, so grab the size of an element + // in bytes. + size_t sizeofElem = SAT->getElementType()->getPrimitiveSizeInBits() / 8; + + ConstantInt *Const = + cast<ConstantInt>(CE->getOperand(CE->getNumOperands() - 1)); + size_t indx = Const->getZExtValue(); + return ReplaceInstUsesWith(CI, + ConstantInt::get(ReturnTy, + ((numElems - indx) * sizeofElem))); + } + } + + // TODO: Add more Instruction types here. + } } diff --git a/test/Transforms/InstCombine/objsize.ll b/test/Transforms/InstCombine/objsize.ll new file mode 100644 index 0000000000..13bb487c13 --- /dev/null +++ b/test/Transforms/InstCombine/objsize.ll @@ -0,0 +1,30 @@ +; RUN: opt < %s -instcombine -S | FileCheck %s +@a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*> +@.str = private constant [8 x i8] c"abcdefg\00" ; <[8 x i8]*> + +define i32 @foo() nounwind { +; CHECK: @foo +; CHECK-NEXT: ret i32 60 + %1 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false) + ret i32 %1 +} + +define i8* @bar() nounwind { +; CHECK: @bar +entry: + %retval = alloca i8* + %0 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false) + %cmp = icmp ne i32 %0, -1 +; CHECK: br i1 true + br i1 %cmp, label %cond.true, label %cond.false + +cond.true: + %1 = load i8** %retval; + ret i8* %1; + +cond.false: + %2 = load i8** %retval; + ret i8* %2; +} + +declare i32 @llvm.objectsize.i32(i8*, i1) nounwind readonly
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