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[SCEV] teach SCEV symbolical execution about overflow intrinsics folding. 

Differential Revision: https://reviews.llvm.org/D64422

llvm-svn: 365726
This commit is contained in:
Chen Zheng 2019-07-11 02:18:22 +00:00
parent e837847ec6
commit 627095ec5b
3 changed files with 132 additions and 1 deletions
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3
llvm/lib/Analysis/ConstantFolding.cpp
View File

@ -1036,6 +1036,9 @@ Constant *ConstantFoldInstOperandsImpl(const Value *InstOrCE, unsigned Opcode,
return ConstantExpr::getSelect(Ops[0], Ops[1], Ops[2]);
case Instruction::ExtractElement:
return ConstantExpr::getExtractElement(Ops[0], Ops[1]);
case Instruction::ExtractValue:
return ConstantExpr::getExtractValue(
Ops[0], dyn_cast<ExtractValueInst>(InstOrCE)->getIndices());
case Instruction::InsertElement:
return ConstantExpr::getInsertElement(Ops[0], Ops[1], Ops[2]);
case Instruction::ShuffleVector:

2
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -7674,7 +7674,7 @@ ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
static bool CanConstantFold(const Instruction *I) {
if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I) ||
isa<LoadInst>(I))
isa<LoadInst>(I) || isa<ExtractValueInst>(I))
return true;
if (const CallInst *CI = dyn_cast<CallInst>(I))

128
llvm/test/Analysis/ScalarEvolution/overflow-intrinsics-trip-count.ll Normal file
View File

@ -0,0 +1,128 @@
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
declare { i16, i1 } @llvm.sadd.with.overflow.i16(i16, i16) nounwind readnone
declare { i16, i1 } @llvm.uadd.with.overflow.i16(i16, i16) nounwind readnone
declare { i16, i1 } @llvm.ssub.with.overflow.i16(i16, i16) nounwind readnone
declare { i16, i1 } @llvm.usub.with.overflow.i16(i16, i16) nounwind readnone
declare { i16, i1 } @llvm.smul.with.overflow.i16(i16, i16) nounwind readnone
declare { i16, i1 } @llvm.umul.with.overflow.i16(i16, i16) nounwind readnone
; CHECK-LABEL: Classifying expressions for: @uadd_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 35
define void @uadd_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ 65500, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.uadd.with.overflow.i16(i16 %indvars.iv, i16 1)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
; CHECK-LABEL: Classifying expressions for: @sadd_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 67
define void @sadd_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ 32700, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.sadd.with.overflow.i16(i16 %indvars.iv, i16 1)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
; CHECK-LABEL: Classifying expressions for: @usub_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 50
define void @usub_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ 50, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.usub.with.overflow.i16(i16 %indvars.iv, i16 1)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
; CHECK-LABEL: Classifying expressions for: @ssub_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 68
define void @ssub_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ -32700, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.ssub.with.overflow.i16(i16 %indvars.iv, i16 1)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
; CHECK-LABEL: Classifying expressions for: @smul_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 14
define void @smul_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ 1, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.smul.with.overflow.i16(i16 %indvars.iv, i16 2)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}
; CHECK-LABEL: Classifying expressions for: @umul_exhaustive
; CHECK: Loop %for.body: backedge-taken count is 15
define void @umul_exhaustive() {
entry:
br i1 undef, label %for.end, label %for.body.preheader
for.body.preheader: ; preds = %entry
br label %for.body
for.body: ; preds = %for.body.preheader, %for.body
%indvars.iv = phi i16 [ %math, %for.body ], [ 1, %for.body.preheader ]
%0 = call { i16, i1 } @llvm.umul.with.overflow.i16(i16 %indvars.iv, i16 2)
%math = extractvalue { i16, i1 } %0, 0
%ov = extractvalue { i16, i1 } %0, 1
br i1 %ov, label %for.end, label %for.body
for.end: ; preds = %for.body, %entry
ret void
}