[llvm] r292583 - NewGVN: Fix PR 31682, an overactive assert.
Daniel Berlin via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 19 22:38:41 PST 2017
Author: dannyb
Date: Fri Jan 20 00:38:41 2017
New Revision: 292583
URL: http://llvm.org/viewvc/llvm-project?rev=292583&view=rev
Log:
NewGVN: Fix PR 31682, an overactive assert.
Part of the assert has been left active for further debugging.
The other part has been turned into a stat for tracking for the
moment.
Added:
llvm/trunk/test/Transforms/NewGVN/pr31682.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp?rev=292583&r1=292582&r2=292583&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/NewGVN.cpp Fri Jan 20 00:38:41 2017
@@ -85,6 +85,8 @@ STATISTIC(NumGVNLeaderChanges, "Number o
STATISTIC(NumGVNSortedLeaderChanges, "Number of sorted leader changes");
STATISTIC(NumGVNAvoidedSortedLeaderChanges,
"Number of avoided sorted leader changes");
+STATISTIC(NumGVNNotMostDominatingLeader,
+ "Number of times a member dominated it's new classes' leader");
//===----------------------------------------------------------------------===//
// GVN Pass
@@ -1071,16 +1073,20 @@ void NewGVN::moveValueToNewCongruenceCla
if (I == OldClass->NextLeader.first)
OldClass->NextLeader = {nullptr, ~0U};
- // The new instruction and new class leader may either be siblings in the
- // dominator tree, or the new class leader should dominate the new member
- // instruction. We simply check that the member instruction does not properly
- // dominate the new class leader.
- assert((!isa<Instruction>(NewClass->RepLeader) || !NewClass->RepLeader ||
- I == NewClass->RepLeader ||
- !DT->properlyDominates(
- I->getParent(),
- cast<Instruction>(NewClass->RepLeader)->getParent())) &&
- "New class for instruction should not be dominated by instruction");
+ // It's possible, though unlikely, for us to discover equivalences such
+ // that the current leader does not dominate the old one.
+ // This statistic tracks how often this happens.
+ // We assert on phi nodes when this happens, currently, for debugging, because
+ // we want to make sure we name phi node cycles properly.
+ if (isa<Instruction>(NewClass->RepLeader) && NewClass->RepLeader &&
+ I != NewClass->RepLeader &&
+ DT->properlyDominates(
+ I->getParent(),
+ cast<Instruction>(NewClass->RepLeader)->getParent())) {
+ ++NumGVNNotMostDominatingLeader;
+ assert(!isa<PHINode>(I) &&
+ "New class for instruction should not be dominated by instruction");
+ }
if (NewClass->RepLeader != I) {
auto DFSNum = InstrDFS.lookup(I);
Added: llvm/trunk/test/Transforms/NewGVN/pr31682.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/NewGVN/pr31682.ll?rev=292583&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/NewGVN/pr31682.ll (added)
+++ llvm/trunk/test/Transforms/NewGVN/pr31682.ll Fri Jan 20 00:38:41 2017
@@ -0,0 +1,42 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -basicaa -newgvn -S | FileCheck %s
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.foo = type { i32, i32, [2 x [4 x [6 x [6 x i16]]]] }
+
+ at global = external global %struct.foo*
+
+define void @bar() {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: [[TMP:%.*]] = load %struct.foo*, %struct.foo** @global
+; CHECK-NEXT: br label [[BB2:%.*]]
+; CHECK: bb2:
+; CHECK-NEXT: [[TMP4:%.*]] = getelementptr [[STRUCT_FOO:%.*]], %struct.foo* [[TMP]], i64 0, i32 1
+; CHECK-NEXT: br i1 undef, label [[BB2]], label [[BB7:%.*]]
+; CHECK: bb7:
+; CHECK-NEXT: br label [[BB10:%.*]]
+; CHECK: bb10:
+; CHECK-NEXT: br label [[BB10]]
+;
+bb:
+ %tmp = load %struct.foo*, %struct.foo** @global
+ %tmp1 = getelementptr %struct.foo, %struct.foo* %tmp
+ br label %bb2
+
+bb2: ; preds = %bb2, %bb
+ %tmp3 = phi %struct.foo* [ undef, %bb ], [ %tmp6, %bb2 ]
+ %tmp4 = getelementptr %struct.foo, %struct.foo* %tmp3, i64 0, i32 1
+ %tmp5 = load i32, i32* %tmp4
+ %tmp6 = load %struct.foo*, %struct.foo** @global
+ br i1 undef, label %bb2, label %bb7
+
+bb7: ; preds = %bb2
+ %tmp8 = phi %struct.foo* [ %tmp6, %bb2 ]
+ %tmp9 = getelementptr %struct.foo, %struct.foo* %tmp8, i64 0, i32 1
+ br label %bb10
+
+bb10: ; preds = %bb10, %bb7
+ %tmp11 = load i32, i32* %tmp9
+ br label %bb10
+}
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