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Make ConstantFoldConstantExpression recursively visit the entire

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ConstantExpr, not just the top-level operator. This allows it to
fold many more constants.

Also, make GlobalOpt call ConstantFoldConstantExpression on
GlobalVariable initializers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89659 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-11-23 16:22:21 +00:00
parent 8f3817f505
commit 01b97dd01e
5 changed files with 31 additions and 5 deletions
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13
lib/Analysis/ConstantFolding.cpp
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@ -671,8 +671,13 @@ Constant *llvm::ConstantFoldInstruction(Instruction *I, const TargetData *TD) {
Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
const TargetData *TD) {
SmallVector<Constant*, 8> Ops;
for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
Ops.push_back(cast<Constant>(*i));
for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i) {
Constant *NewC = cast<Constant>(*i);
// Recursively fold the ConstantExpr's operands.
if (ConstantExpr *NewCE = dyn_cast<ConstantExpr>(NewC))
NewC = ConstantFoldConstantExpression(NewCE, TD);
Ops.push_back(NewC);
}
if (CE->isCompare())
return ConstantFoldCompareInstOperands(CE->getPredicate(), Ops[0], Ops[1],
@ -687,6 +692,10 @@ Constant *llvm::ConstantFoldConstantExpression(ConstantExpr *CE,
/// attempting to fold instructions like loads and stores, which have no
/// constant expression form.
///
/// TODO: This function neither utilizes nor preserves nsw/nuw/inbounds/etc
/// information, due to only being passed an opcode and operands. Constant
/// folding using this function strips this information.
///
Constant *llvm::ConstantFoldInstOperands(unsigned Opcode, const Type *DestTy,
Constant* const* Ops, unsigned NumOps,
const TargetData *TD) {

9
lib/Transforms/IPO/GlobalOpt.cpp
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@ -1898,6 +1898,15 @@ bool GlobalOpt::OptimizeGlobalVars(Module &M) {
// Global variables without names cannot be referenced outside this module.
if (!GV->hasName() && !GV->isDeclaration())
GV->setLinkage(GlobalValue::InternalLinkage);
// Simplify the initializer.
if (GV->hasInitializer())
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) {
TargetData *TD = getAnalysisIfAvailable<TargetData>();
Constant *New = ConstantFoldConstantExpression(CE, TD);
if (New && New != CE)
GV->setInitializer(New);
}
// Do more involved optimizations if the global is internal.
if (!GV->isConstant() && GV->hasLocalLinkage() &&
GV->hasInitializer())
Changed |= ProcessInternalGlobal(GV, GVI);

8
test/Transforms/GlobalOpt/constantfold-initializers.ll Normal file
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@ -0,0 +1,8 @@
; RUN: opt < %s -S -globalopt | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
@.str91250 = global [3 x i8] zeroinitializer
; CHECK: @A = global i1 false
@A = global i1 icmp ne (i64 sub nsw (i64 ptrtoint (i8* getelementptr inbounds ([3 x i8]* @.str91250, i64 0, i64 1) to i64), i64 ptrtoint ([3 x i8]* @.str91250 to i64)), i64 1)

4
test/Transforms/InstCombine/cast.ll
View File

@ -103,7 +103,7 @@ define i32* @test12() {
%p = malloc [4 x i8] ; <[4 x i8]*> [#uses=1]
%c = bitcast [4 x i8]* %p to i32* ; <i32*> [#uses=1]
ret i32* %c
; CHECK: %malloccall = tail call i8* @malloc(i32 ptrtoint ([4 x i8]* getelementptr ([4 x i8]* null, i32 1) to i32))
; CHECK: %malloccall = tail call i8* @malloc(i32 4)
; CHECK: ret i32* %c
}
@ -275,7 +275,7 @@ define void @test32(double** %tmp) {
%tmp8.upgrd.1 = bitcast [16 x i8]* %tmp8 to double* ; <double*> [#uses=1]
store double* %tmp8.upgrd.1, double** %tmp
ret void
; CHECK: %malloccall = tail call i8* @malloc(i32 ptrtoint ([16 x i8]* getelementptr ([16 x i8]* null, i32 1) to i32))
; CHECK: %malloccall = tail call i8* @malloc(i32 16)
; CHECK: %tmp8.upgrd.1 = bitcast i8* %malloccall to double*
; CHECK: store double* %tmp8.upgrd.1, double** %tmp
; CHECK: ret void

2
test/Transforms/InstCombine/shufflevec-constant.ll
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@ -1,4 +1,4 @@
; RUN: opt < %s -instcombine -S | grep "2 x float"
; RUN: opt < %s -instcombine -S | grep {ret <4 x float> <float 0.000000e+00, float 0.000000e+00, float 0x7FF0000000000000, float 0x7FF0000000000000>}
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"
target triple = "i386-apple-darwin9"