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[InstCombine] Call getCmpPredicateForMinMax only with a valid SPF 

Summary:
There are `SelectPatternFlavor`s that don't represent min or max idioms,
and we should not be passing those to `getCmpPredicateForMinMax`.

Fixes PR25745.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D15249

llvm-svn: 254869
This commit is contained in:
Sanjoy Das 2015-12-05 23:44:22 +00:00
parent e66b73fb0c
commit 9fe86d90ab
3 changed files with 30 additions and 1 deletions
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5
llvm/include/llvm/Analysis/ValueTracking.h
View File

@ -412,6 +412,11 @@ namespace llvm {
bool Ordered; /// When implementing this min/max pattern as bool Ordered; /// When implementing this min/max pattern as
/// fcmp; select, does the fcmp have to be /// fcmp; select, does the fcmp have to be
/// ordered? /// ordered?
/// \brief Return true if \p SPF is a min or a max pattern.
static bool isMinOrMax(SelectPatternFlavor SPF) {
return !(SPF == SPF_UNKNOWN || SPF == SPF_ABS || SPF == SPF_NABS);
}
}; };
/// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind /// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
/// and providing the out parameter results if we successfully match. /// and providing the out parameter results if we successfully match.

6
llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@ -1070,7 +1070,7 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp); SelectPatternResult SPR = matchSelectPattern(&SI, LHS, RHS, &CastOp);
auto SPF = SPR.Flavor; auto SPF = SPR.Flavor;
if (SPF) { if (SelectPatternResult::isMinOrMax(SPF)) {
// Canonicalize so that type casts are outside select patterns. // Canonicalize so that type casts are outside select patterns.
if (LHS->getType()->getPrimitiveSizeInBits() != if (LHS->getType()->getPrimitiveSizeInBits() !=
SI.getType()->getPrimitiveSizeInBits()) { SI.getType()->getPrimitiveSizeInBits()) {
@ -1091,11 +1091,15 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
SI.getType()); SI.getType());
return ReplaceInstUsesWith(SI, NewSI); return ReplaceInstUsesWith(SI, NewSI);
} }
}
if (SPF) {
// MAX(MAX(a, b), a) -> MAX(a, b) // MAX(MAX(a, b), a) -> MAX(a, b)
// MIN(MIN(a, b), a) -> MIN(a, b) // MIN(MIN(a, b), a) -> MIN(a, b)
// MAX(MIN(a, b), a) -> a // MAX(MIN(a, b), a) -> a
// MIN(MAX(a, b), a) -> a // MIN(MAX(a, b), a) -> a
// ABS(ABS(a)) -> ABS(a)
// NABS(NABS(a)) -> NABS(a)
if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor) if (SelectPatternFlavor SPF2 = matchSelectPattern(LHS, LHS2, RHS2).Flavor)
if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2, if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
SI, SPF, RHS)) SI, SPF, RHS))

20
llvm/test/Transforms/InstCombine/pr25745.ll Normal file
View File

@ -0,0 +1,20 @@
; RUN: opt -S -instcombine < %s | FileCheck %s
; Checking for a crash
declare void @use.i1(i1 %val)
declare void @use.i64(i64 %val)
define i64 @f(i32 %x) {
; CHECK-LABEL: @f(
entry:
%x.wide = sext i32 %x to i64
%minus.x = sub i32 0, %x
%minus.x.wide = sext i32 %minus.x to i64
%c = icmp slt i32 %x, 0
%val = select i1 %c, i64 %x.wide, i64 %minus.x.wide
call void @use.i1(i1 %c)
call void @use.i64(i64 %x.wide)
ret i64 %val
; CHECK: ret i64 %val
}