From 3dfd7bf5110c47e99fd0fcce96122b90f699ca3a Mon Sep 17 00:00:00 2001 From: Nick Lewycky Date: Sun, 25 May 2008 20:56:15 +0000 Subject: [PATCH] "ret (constexpr)" can't be folded into a Constant. Add a method to Analysis/ConstantFolding to fold ConstantExpr's, then make instcombine use it to try to use targetdata to fold constant expressions on void instructions. Also extend the icmp(inttoptr, inttoptr) folding to handle the case where int size != ptr size. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51559 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ConstantFolding.h | 6 ++ lib/Analysis/ConstantFolding.cpp | 61 ++++++++++++++----- .../Scalar/InstructionCombining.cpp | 10 +++ .../InstCombine/2008-05-18-FoldIntToPtr.ll | 13 ++++ 4 files changed, 74 insertions(+), 16 deletions(-) create mode 100644 test/Transforms/InstCombine/2008-05-18-FoldIntToPtr.ll diff --git a/include/llvm/Analysis/ConstantFolding.h b/include/llvm/Analysis/ConstantFolding.h index a22913a0b90..bf360f7e884 100644 --- a/include/llvm/Analysis/ConstantFolding.h +++ b/include/llvm/Analysis/ConstantFolding.h @@ -30,6 +30,12 @@ namespace llvm { /// Constant *ConstantFoldInstruction(Instruction *I, const TargetData *TD = 0); +/// ConstantFoldConstantExpression - Attempt to fold the constant expression +/// using the specified TargetData. If successful, the constant result is +/// result is returned, if not, null is returned. +Constant *ConstantFoldConstantExpression(ConstantExpr *CE, + const TargetData *TD); + /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the /// specified operands. If successful, the constant result is returned, if not, /// null is returned. Note that this function can fail when attempting to diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp index d933dd8d403..43597c85f16 100644 --- a/lib/Analysis/ConstantFolding.cpp +++ b/lib/Analysis/ConstantFolding.cpp @@ -312,6 +312,25 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) { &Ops[0], Ops.size(), TD); } +/// ConstantFoldConstantExpression - Attempt to fold the constant expression +/// using the specified TargetData. If successful, the constant result is +/// result is returned, if not, null is returned. +Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE, + const TargetData *TD) { + assert(TD && "ConstantFoldConstantExpression requires a valid TargetData."); + + SmallVector Ops; + for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i) + Ops.push_back(cast(*i)); + + if (CE->isCompare()) + return ConstantFoldCompareInstOperands(CE->getPredicate(), + &Ops[0], Ops.size(), TD); + else + return ConstantFoldInstOperands(CE->getOpcode(), CE->getType(), + &Ops[0], Ops.size(), TD); +} + /// ConstantFoldInstOperands - Attempt to constant fold an instruction with the /// specified opcode and operands. If successful, the constant result is /// returned, if not, null is returned. Note that this function can fail when @@ -398,7 +417,7 @@ Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate, const TargetData *TD) { // fold: icmp (inttoptr x), null -> icmp x, 0 // fold: icmp (ptrtoint x), 0 -> icmp x, null - // fold: icmp (inttoptr x), (inttoptr y) -> icmp x, y + // fold: icmp (inttoptr x), (inttoptr y) -> icmp trunc/zext x, trunc/zext y // fold: icmp (ptrtoint x), (ptrtoint y) -> icmp x, y // // ConstantExpr::getCompare cannot do this, because it doesn't have TD @@ -426,21 +445,31 @@ Constant *llvm::ConstantFoldCompareInstOperands(unsigned Predicate, } } - if (TD && isa(Ops[1]) && - cast(Ops[1])->getOpcode() == CE0->getOpcode()) { - const Type *IntPtrTy = TD->getIntPtrType(); - // Only do this transformation if the int is intptrty in size, otherwise - // there is a truncation or extension that we aren't modeling. - if ((CE0->getOpcode() == Instruction::IntToPtr && - CE0->getOperand(0)->getType() == IntPtrTy && - Ops[1]->getOperand(0)->getType() == IntPtrTy) || - (CE0->getOpcode() == Instruction::PtrToInt && - CE0->getType() == IntPtrTy && - CE0->getOperand(0)->getType() == Ops[1]->getOperand(0)->getType())) { - Constant *NewOps[] = { - CE0->getOperand(0), cast(Ops[1])->getOperand(0) - }; - return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD); + if (ConstantExpr *CE1 = dyn_cast(Ops[1])) { + if (TD && CE0->getOpcode() == CE1->getOpcode()) { + const Type *IntPtrTy = TD->getIntPtrType(); + + if (CE0->getOpcode() == Instruction::IntToPtr) { + // Convert the integer value to the right size to ensure we get the + // proper extension or truncation. + Constant *C0 = ConstantExpr::getIntegerCast(CE0->getOperand(0), + IntPtrTy, false); + Constant *C1 = ConstantExpr::getIntegerCast(CE1->getOperand(0), + IntPtrTy, false); + Constant *NewOps[] = { C0, C1 }; + return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD); + } + + // Only do this transformation if the int is intptrty in size, otherwise + // there is a truncation or extension that we aren't modeling. + if ((CE0->getOpcode() == Instruction::PtrToInt && + CE0->getType() == IntPtrTy && + CE0->getOperand(0)->getType() == CE1->getOperand(0)->getType())) { + Constant *NewOps[] = { + CE0->getOperand(0), CE1->getOperand(0) + }; + return ConstantFoldCompareInstOperands(Predicate, NewOps, 2, TD); + } } } } diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index a6cbc201637..20204154d0e 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -11887,6 +11887,16 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) { continue; } + if (TD && I->getType()->getTypeID() == Type::VoidTyID) { + // See if we can constant fold its operands. + for (User::op_iterator i = I->op_begin(), e = I->op_end(); i != e; ++i) { + if (ConstantExpr *CE = dyn_cast(i)) { + if (Constant *NewC = ConstantFoldConstantExpression(CE, TD)) + i->set(NewC); + } + } + } + // See if we can trivially sink this instruction to a successor basic block. // FIXME: Remove GetResultInst test when first class support for aggregates // is implemented. diff --git a/test/Transforms/InstCombine/2008-05-18-FoldIntToPtr.ll b/test/Transforms/InstCombine/2008-05-18-FoldIntToPtr.ll new file mode 100644 index 00000000000..e994399e423 --- /dev/null +++ b/test/Transforms/InstCombine/2008-05-18-FoldIntToPtr.ll @@ -0,0 +1,13 @@ +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i1 false} | count 2 +; PR2329 + +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-f80:32:32" +target triple = "i386-pc-linux-gnu" + +define i1 @f1() { + ret i1 icmp eq (i8* inttoptr (i32 1 to i8*), i8* inttoptr (i32 2 to i8*)) +} + +define i1 @f2() { + ret i1 icmp eq (i8* inttoptr (i16 1 to i8*), i8* inttoptr (i16 2 to i8*)) +}