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[NewGVN] Make sure we do not add a user to itself.

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If we simplify an instruction to itself, we do not need to add a user to
itself. For congruence classes with a defining expression, we already
use a similar logic.

Fixes PR38259.

Reviewers: davide, efriedma, mcrosier

Reviewed By: davide

Differential Revision: https://reviews.llvm.org/D51168

llvm-svn: 346335
This commit is contained in:
Florian Hahn 2018-11-07 17:20:07 +00:00
parent 9fe36dfbc6
commit 97c8f6a46c
2 changed files with 34 additions and 3 deletions
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4
lib/Transforms/Scalar/NewGVN.cpp
View File

@ -1086,9 +1086,13 @@ const Expression *NewGVN::checkSimplificationResults(Expression *E,
CongruenceClass *CC = ValueToClass.lookup(V);
if (CC) {
if (CC->getLeader() && CC->getLeader() != I) {
// If we simplified to something else, we need to communicate
// that we're users of the value we simplified to.
if (I != V) {
// Don't add temporary instructions to the user lists.
if (!AllTempInstructions.count(I))
addAdditionalUsers(V, I);
}
return createVariableOrConstant(CC->getLeader());
}
if (CC->getDefiningExpr()) {

27
test/Transforms/NewGVN/simp-to-self.ll Normal file
View File

@ -0,0 +1,27 @@
; RUN: opt -S < %s -newgvn | FileCheck %s
; CHECK-LABEL: for.cond:
; CHECK-NEXT: %lv = load i32, i32* bitcast (i64* @a to i32*)
; CHECK-NEXT: %bf.clear = and i32 %lv, -131072
; CHECK-NEXT: %bf.set = or i32 1, %bf.clear
; CHECK-NEXT: br i1 %bc, label %for.cond, label %exit
@a = external global i64
define void @fn1(i1 %bc) {
entry:
br label %for.cond
for.cond: ; preds = %for.cond1.1, %entry
%tmp = phi i1 [ undef, %entry ], [ 1, %for.cond ]
%conv = zext i1 %tmp to i32
%lv = load i32, i32* bitcast (i64* @a to i32*)
%bf.clear = and i32 %lv, -131072
%bf.set = or i32 %conv, %bf.clear
%bf.clear.1 = and i32 %bf.set, -131072
%bf.set.1 = or i32 1, %bf.clear.1
br i1 %bc, label %for.cond, label %exit
exit: ; preds = %for.cond1
store i32 %bf.set.1, i32* bitcast (i64* @a to i32*)
ret void
}