diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCalls.cpp | 72 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/objsize.ll | 14 |
2 files changed, 61 insertions, 25 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp index ebadfbc..f798220 100644 --- a/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -635,43 +635,69 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { case Intrinsic::objectsize: { const Type *ReturnTy = CI.getType(); Value *Op1 = II->getOperand(1); + + // If we've got a GEP we're going to do some calculations + size_t GEPindex = 0; - // 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. + // Strip any casts we see and continue processing. + Op1 = Op1->stripPointerCasts(); + + // Make sure we can reliably know the size. + if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op1)) + if (!GV->hasDefinitiveInitializer()) break; + if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Op1)) { - // If this isn't a GEP give up. - if (CE->getOpcode() != Instruction::GetElementPtr) return 0; + // If this isn't a GEP give up. + if (CE->getOpcode() != Instruction::GetElementPtr) break; - const PointerType *ObjTy = - reinterpret_cast<const PointerType*>(CE->getOperand(0)->getType()); + // If this isn't guaranteed to be inbounds, give up. + bool OOB = false; + GEPOperator *GEPO = cast<GEPOperator>(Op1); + if (!GEPO->isInBounds()) OOB = true; + + for (int i = GEPO->getNumIndices() - 1; i > 0; i--) { + if (Constant *C = dyn_cast<Constant>(GEPO->getOperand(i))) + if (C->isNullValue()) + continue; + + OOB = true; + } + + // If we're guaranteed to be out of bounds just return that there's + // no room left. + if (OOB) return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, 0)); + + // Tell the later calculation that we have an offset and what + // it is. + Op1 = CE->getOperand(0); + ConstantInt *Const = + cast<ConstantInt>(CE->getOperand(CE->getNumOperands() - 1)); + GEPindex = Const->getZExtValue(); + } - if (const ArrayType *AT = dyn_cast<ArrayType>(ObjTy->getElementType())) { + // This may be a pointer to an array. If we have an index from earlier + // use that too. + if (const PointerType *PT = dyn_cast<PointerType>(Op1->getType())) { + if (const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType())) { // Deal with multi-dimensional arrays const ArrayType *SAT = AT; while ((AT = dyn_cast<ArrayType>(AT->getElementType()))) SAT = AT; - - size_t numElems = SAT->getNumElements(); - - // If numElems is 0, we don't know how large the array is so we can't - // make any determinations yet. - if (numElems == 0) break; // 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))); + // in bytes and the number of elements. + if (!SAT->isSized() || !TD) break; + + size_t sizeofElem = TD->getTypeAllocSize(SAT->getElementType()); + size_t numElems = SAT->getNumElements(); + size_t remSize = (numElems - GEPindex) * sizeofElem; + return ReplaceInstUsesWith(CI, ConstantInt::get(ReturnTy, remSize)); } } + // TODO: Add more types here. + // TODO: Check for type isSized() here as well. } } diff --git a/test/Transforms/InstCombine/objsize.ll b/test/Transforms/InstCombine/objsize.ll index fed067c..bdb3e09 100644 --- a/test/Transforms/InstCombine/objsize.ll +++ b/test/Transforms/InstCombine/objsize.ll @@ -1,5 +1,9 @@ +; Test a pile of objectsize bounds checking. ; RUN: opt < %s -instcombine -S | FileCheck %s -@a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*> +; We need target data to get the sizes of the arrays and structures. +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" + +@a = private 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 { @@ -27,6 +31,13 @@ cond.false: ret i8* %2; } +define i32 @f() nounwind { +; CHECK: @f +; CHECK-NEXT: ret i32 0 + %1 = call i32 @llvm.objectsize.i32(i8* getelementptr ([60 x i8]* @a, i32 1, i32 0), i1 false) + ret i32 %1 +} + @window = external global [0 x i8] define i1 @baz() nounwind { @@ -37,5 +48,4 @@ define i1 @baz() nounwind { ret i1 %2 } - declare i32 @llvm.objectsize.i32(i8*, i1) nounwind readonly
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