maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/test/Transforms/InstCombine/pr44245.ll

Ignoring revisions in .git-blame-ignore-revs. Click here to bypass and see the normal blame view.

192 lines
7.6 KiB
LLVM
Raw Normal View History

[InstCombine] Fix infinite loop due to bitcast <-> phi transforms Fix for https://bugs.llvm.org/show_bug.cgi?id=44245. The optimizeBitCastFromPhi() and FoldPHIArgOpIntoPHI() end up fighting against each other, because optimizeBitCastFromPhi() assumes that bitcasts of loads will get folded. This doesn't happen here, because a dangling phi node prevents the one-use fold in https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp#L620-L628 from triggering. This patch fixes the issue by explicitly performing the load combine as part of the bitcast of phi transform. Other attempts to force the load to be combined first were ultimately too unreliable. Differential Revision: https://reviews.llvm.org/D71164
2020-01-14 01:57:14 +08:00
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine -instcombine-infinite-loop-threshold=2 < %s | FileCheck %s
; This used to cause on infinite instcombine loop.
define void @test(i1 %c) {
; CHECK-LABEL: @test(
; CHECK-NEXT: bb16:
; CHECK-NEXT: br i1 [[C:%.*]], label [[BB17:%.*]], label [[BB24:%.*]]
; CHECK: bb17:
; CHECK-NEXT: [[TMP0:%.*]] = phi i8* [ [[TMP1:%.*]], [[BB47:%.*]] ], [ undef, [[BB16:%.*]] ]
; CHECK-NEXT: store i8* [[TMP0]], i8** undef, align 8
; CHECK-NEXT: ret void
; CHECK: bb24:
; CHECK-NEXT: br i1 [[C]], label [[BB44:%.*]], label [[BB49:%.*]]
; CHECK: bb44:
; CHECK-NEXT: [[TMP467:%.*]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb47:
; CHECK-NEXT: [[TMP1]] = phi i8* [ [[TMP2:%.*]], [[BB150:%.*]] ], [ [[TMP1221:%.*]], [[BB119:%.*]] ], [ [[TMP1032:%.*]], [[BB101:%.*]] ], [ [[TMP933:%.*]], [[BB91:%.*]] ], [ [[TMP834:%.*]], [[BB81:%.*]] ], [ [[TMP705:%.*]], [[BB67:%.*]] ], [ [[TMP586:%.*]], [[BB56:%.*]] ], [ [[TMP467]], [[BB44]] ]
; CHECK-NEXT: br label [[BB17]]
; CHECK: bb49:
; CHECK-NEXT: br i1 [[C]], label [[BB56]], label [[BB59:%.*]]
; CHECK: bb56:
; CHECK-NEXT: [[TMP586]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb59:
; CHECK-NEXT: br i1 [[C]], label [[BB67]], label [[BB71:%.*]]
; CHECK: bb67:
; CHECK-NEXT: [[TMP705]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb71:
; CHECK-NEXT: br i1 [[C]], label [[BB81]], label [[BB84:%.*]]
; CHECK: bb81:
; CHECK-NEXT: [[TMP834]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb84:
; CHECK-NEXT: br i1 [[C]], label [[BB91]], label [[BB94:%.*]]
; CHECK: bb91:
; CHECK-NEXT: [[TMP933]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb94:
; CHECK-NEXT: br i1 [[C]], label [[BB101]], label [[BB104:%.*]]
; CHECK: bb101:
; CHECK-NEXT: [[TMP1032]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb104:
; CHECK-NEXT: br i1 [[C]], label [[BB119]], label [[BB123:%.*]]
; CHECK: bb119:
; CHECK-NEXT: [[TMP1221]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb123:
; CHECK-NEXT: br i1 [[C]], label [[BB147:%.*]], label [[BB152:%.*]]
; CHECK: bb147:
; CHECK-NEXT: [[TMP1499:%.*]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
; CHECK-NEXT: br label [[BB150]]
; CHECK: bb150:
; CHECK-NEXT: [[TMP2]] = phi i8* [ [[TMP1848:%.*]], [[BB152]] ], [ [[TMP1499]], [[BB147]] ]
; CHECK-NEXT: br label [[BB47]]
; CHECK: bb152:
; CHECK-NEXT: [[TMP1848]] = load i8*, i8** inttoptr (i64 16 to i8**), align 16
[InstCombine] Don't simplify calls without uses When simplifying a call without uses, replaceInstUsesWith() is going to do nothing, but we'll skip all following folds. We can only run into this problem with calls that both simplify and are not trivially dead if unused, which currently seems to happen only with calls to undef, as the test diff shows. When extending SimplifyCall() to handle "returned" attributes, this becomes a much bigger problem, so I'm fixing this first. Differential Revision: https://reviews.llvm.org/D75814
2020-03-08 03:21:09 +08:00
; CHECK-NEXT: store i1 true, i1* undef, align 1
[InstCombine] Fix infinite loop due to bitcast <-> phi transforms Fix for https://bugs.llvm.org/show_bug.cgi?id=44245. The optimizeBitCastFromPhi() and FoldPHIArgOpIntoPHI() end up fighting against each other, because optimizeBitCastFromPhi() assumes that bitcasts of loads will get folded. This doesn't happen here, because a dangling phi node prevents the one-use fold in https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp#L620-L628 from triggering. This patch fixes the issue by explicitly performing the load combine as part of the bitcast of phi transform. Other attempts to force the load to be combined first were ultimately too unreliable. Differential Revision: https://reviews.llvm.org/D71164
2020-01-14 01:57:14 +08:00
; CHECK-NEXT: br label [[BB150]]
;
bb16: ; preds = %bb
br i1 %c, label %bb17, label %bb24
bb17: ; preds = %bb47, %bb17
%0 = phi i8* [ %1, %bb47 ], [ undef, %bb16 ]
store i8* %0, i8** undef, align 8
ret void
bb24: ; preds = %bb24
br i1 %c, label %bb44, label %bb49
bb44: ; preds = %bb43
%tmp46 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb47: ; preds = %bb150, %bb119, %bb101, %bb91, %bb81, %bb67, %bb56, %bb44
%.in1 = phi i64* [ %.in, %bb150 ], [ %tmp122, %bb119 ], [ %tmp103, %bb101 ], [ %tmp93, %bb91 ], [ %tmp83, %bb81 ], [ %tmp70, %bb67 ], [ %tmp58, %bb56 ], [ %tmp46, %bb44 ]
%1 = bitcast i64* %.in1 to i8*
br label %bb17
bb49: ; preds = %bb49
br i1 %c, label %bb56, label %bb59
bb56: ; preds = %bb55
%tmp58 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb59: ; preds = %bb59
br i1 %c, label %bb67, label %bb71
bb67: ; preds = %bb66
%tmp70 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb71: ; preds = %bb71
br i1 %c, label %bb81, label %bb84
bb81: ; preds = %bb80
%tmp83 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb84: ; preds = %bb84
br i1 %c, label %bb91, label %bb94
bb91: ; preds = %bb90
%tmp93 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb94: ; preds = %bb94
br i1 %c, label %bb101, label %bb104
bb101: ; preds = %bb100
%tmp103 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb104: ; preds = %bb104
br i1 %c, label %bb119, label %bb123
bb119: ; preds = %bb118
%tmp122 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb47
bb123: ; preds = %bb123
br i1 %c, label %bb147, label %bb152
bb147: ; preds = %bb146
%tmp149 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
br label %bb150
bb150: ; preds = %bb152, %bb147
%.in = phi i64* [ %tmp184, %bb152 ], [ %tmp149, %bb147 ]
br label %bb47
bb152: ; preds = %bb146
%tmp184 = load i64*, i64** inttoptr (i64 16 to i64**), align 16
call void undef()
br label %bb150
}
; This used to cause an instcombine loop when the problem above was
; addressed in a non-robust fashion.
%type_1 = type {}
%type_2 = type {}
%type_3 = type {}
define void @test_2(i1 %c) local_unnamed_addr {
; CHECK-LABEL: @test_2(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WHILE_COND:%.*]]
; CHECK: while.cond:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: br i1 [[C:%.*]], label [[COND_TRUE133:%.*]], label [[COND_FALSE138:%.*]]
; CHECK: cond.true133:
; CHECK-NEXT: br label [[COND_END144:%.*]]
; CHECK: cond.false138:
[InstCombine] DCE instructions earlier When InstCombine initially populates the worklist, it already performs constant folding and DCE. However, as the instructions are initially visited in program order, this DCE can pick up only the last instruction of a dead chain, the rest would only get picked up in the main InstCombine run. To avoid this, we instead perform the DCE in separate pass over the collected instructions in reverse order, which will allow us to pick up full dead instruction chains. We already need to do this reverse iteration anyway to populate the worklist, so this shouldn't add extra cost. This by itself only fixes a small part of the problem though: The same basic issue also applies during the main InstCombine loop. We generally always want DCE to occur as early as possible, because it will allow one-use folds to happen. Address this by also performing DCE while adding deferred instructions to the main worklist. This drops the number of tests that perform more than 2 InstCombine iterations from ~80 to ~40. There's some spurious test changes due to operand order / icmp toggling. Differential Revision: https://reviews.llvm.org/D75008
2020-02-21 05:42:42 +08:00
; CHECK-NEXT: store %type_2* undef, %type_2** null, align 536870912
[InstCombine] Fix infinite loop due to bitcast <-> phi transforms Fix for https://bugs.llvm.org/show_bug.cgi?id=44245. The optimizeBitCastFromPhi() and FoldPHIArgOpIntoPHI() end up fighting against each other, because optimizeBitCastFromPhi() assumes that bitcasts of loads will get folded. This doesn't happen here, because a dangling phi node prevents the one-use fold in https://github.com/llvm/llvm-project/blob/master/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp#L620-L628 from triggering. This patch fixes the issue by explicitly performing the load combine as part of the bitcast of phi transform. Other attempts to force the load to be combined first were ultimately too unreliable. Differential Revision: https://reviews.llvm.org/D71164
2020-01-14 01:57:14 +08:00
; CHECK-NEXT: br label [[COND_END144]]
; CHECK: cond.end144:
; CHECK-NEXT: br label [[WHILE_COND]]
;
entry:
br label %while.cond
while.cond: ; preds = %cond.end144, %entry
%link.0 = phi %type_2* [ undef, %entry ], [ %cond145, %cond.end144 ]
%os115 = bitcast %type_2* %link.0 to %type_3*
%ou116 = getelementptr inbounds %type_3, %type_3* %os115, i32 0
%os1117 = bitcast %type_3* %ou116 to %type_1*
br label %for.cond
for.cond: ; preds = %while.cond
br i1 %c, label %cond.true133, label %cond.false138
cond.true133: ; preds = %sw.epilog
%0 = load %type_2*, %type_2** undef, align 8
br label %cond.end144
cond.false138: ; preds = %sw.epilog
%1 = load %type_2*, %type_2** undef, align 8
br label %cond.end144
cond.end144: ; preds = %cond.false138, %cond.true133
%cond145 = phi %type_2* [ %0, %cond.true133 ], [ %1, %cond.false138 ]
br label %while.cond
}