Index: lib/Transforms/Utils/Evaluator.cpp =================================================================== --- lib/Transforms/Utils/Evaluator.cpp +++ lib/Transforms/Utils/Evaluator.cpp @@ -190,13 +190,24 @@ } // Handle a constantexpr getelementptr. - if (ConstantExpr *CE = dyn_cast(P)) + if (ConstantExpr *CE = dyn_cast(P)) { if (CE->getOpcode() == Instruction::GetElementPtr && isa(CE->getOperand(0))) { GlobalVariable *GV = cast(CE->getOperand(0)); if (GV->hasDefinitiveInitializer()) return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE); + } else if (CE->getOpcode() == Instruction::BitCast) { + GlobalVariable *GV = dyn_cast(CE->getOperand(0)); + if (GV && GV->hasDefinitiveInitializer()) { + // We should always load from a pointer + assert(P->getType()->isPointerTy()); + auto *ResTy = P->getType()->getContainedType(0); + auto *I = GV->getInitializer(); + if (I->getType()->isPointerTy() && ResTy->isIntegerTy()) + return ConstantExpr::getPtrToInt(I, ResTy); + } } + } return nullptr; // don't know how to evaluate. } @@ -249,10 +260,15 @@ Type *NewTy = cast(Ptr->getType())->getElementType(); + auto TypeConversionSafe = [](Type *VTy, Type *Ty) { + return (VTy->isIntegerTy() && Ty->isPointerTy()) || + VTy->canLosslesslyBitCastTo(Ty); + }; // In order to push the bitcast onto the stored value, a bitcast // from NewTy to Val's type must be legal. If it's not, we can try // introspecting NewTy to find a legal conversion. - while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) { + auto *VTy = Val->getType(); + while (!TypeConversionSafe(VTy, NewTy)) { // If NewTy is a struct, we can convert the pointer to the struct // into a pointer to its first member. // FIXME: This could be extended to support arrays as well. @@ -277,8 +293,9 @@ } // If we found compatible types, go ahead and push the bitcast - // onto the stored value. - Val = ConstantExpr::getBitCast(Val, NewTy); + // onto the stored value or convert it from integer to pointer. + Val = VTy->isIntegerTy() ? ConstantExpr::getIntToPtr(Val, NewTy) + : ConstantExpr::getBitCast(Val, NewTy); DEBUG(dbgs() << "Evaluated bitcast: " << *Val << "\n"); } Index: test/Transforms/GlobalOpt/evaluate-bitcast.ll =================================================================== --- test/Transforms/GlobalOpt/evaluate-bitcast.ll +++ test/Transforms/GlobalOpt/evaluate-bitcast.ll @@ -0,0 +1,28 @@ +; RUN: opt -globalopt -instcombine %s -S -o - | FileCheck %s + +; Static constructor should have been optimized out +; CHECK: i32 @main +; CHECK-NEXT: ret i32 69905 +; CHECK-NOT: _GLOBAL__sub_I_main.cpp + +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-pc-linux-gnu" + +%struct.S = type { %struct.A* } +%struct.A = type { i64, i64 } + +@s = internal local_unnamed_addr global %struct.S zeroinitializer, align 8 +@llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @_GLOBAL__sub_I_main.cpp, i8* null }] +@gA = available_externally dso_local local_unnamed_addr global %struct.A* inttoptr (i64 69905 to %struct.A*), align 8 + +define dso_local i32 @main() local_unnamed_addr { + %1 = load i64, i64* bitcast (%struct.S* @s to i64*), align 8 + %2 = trunc i64 %1 to i32 + ret i32 %2 +} + +define internal void @_GLOBAL__sub_I_main.cpp() section ".text.startup" { + %1 = load i64, i64* bitcast (%struct.A** @gA to i64*), align 8 + store i64 %1, i64* bitcast (%struct.S* @s to i64*), align 8 + ret void +}