[llvm] cfc9298 - [CHR] Fix up phi nodes with unreachable predecessors (PR64594)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 11 00:38:09 PDT 2023
Author: Nikita Popov
Date: 2023-08-11T09:38:01+02:00
New Revision: cfc9298dc588c626a52193260da28a630e103916
URL: https://github.com/llvm/llvm-project/commit/cfc9298dc588c626a52193260da28a630e103916
DIFF: https://github.com/llvm/llvm-project/commit/cfc9298dc588c626a52193260da28a630e103916.diff
LOG: [CHR] Fix up phi nodes with unreachable predecessors (PR64594)
If a block in the CHR region has an unreachable predecessor, then
there will be no edge from that predecessor to the newly cloned
block. However, a phi node entry for it will be left behind. Make
sure that these incoming blocks get dropped as well.
Fixes https://github.com/llvm/llvm-project/issues/64594.
Differential Revision: https://reviews.llvm.org/D157621
Added:
llvm/test/Transforms/PGOProfile/chr-dead-pred.ll
Modified:
llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index 3e3be536defc5d..478e45b95cbdd5 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -1777,6 +1777,21 @@ void CHR::cloneScopeBlocks(CHRScope *Scope,
BasicBlock *NewBB = CloneBasicBlock(BB, VMap, ".nonchr", &F);
NewBlocks.push_back(NewBB);
VMap[BB] = NewBB;
+
+ // Unreachable predecessors will not be cloned and will not have an edge
+ // to the cloned block. As such, also remove them from any phi nodes.
+ // To avoid iterator invalidation, first collect the dead predecessors
+ // from the first phi node, and then perform the actual removal.
+ SmallVector<BasicBlock *> DeadPreds;
+ for (PHINode &PN : NewBB->phis()) {
+ for (BasicBlock *Pred : PN.blocks())
+ if (!DT.isReachableFromEntry(Pred))
+ DeadPreds.push_back(Pred);
+ break;
+ }
+ for (PHINode &PN : make_early_inc_range(NewBB->phis()))
+ for (BasicBlock *Pred : DeadPreds)
+ PN.removeIncomingValue(Pred);
}
// Place the cloned blocks right after the original blocks (right before the
diff --git a/llvm/test/Transforms/PGOProfile/chr-dead-pred.ll b/llvm/test/Transforms/PGOProfile/chr-dead-pred.ll
new file mode 100644
index 00000000000000..bdbf0640035d41
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/chr-dead-pred.ll
@@ -0,0 +1,106 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; RUN: opt -S -passes='require<profile-summary>,chr' < %s | FileCheck %s
+
+define void @test(i1 %c, i1 %c2) !prof !29 {
+; CHECK-LABEL: define void @test
+; CHECK-SAME: (i1 [[C:%.*]], i1 [[C2:%.*]]) !prof [[PROF29:![0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = xor i1 true, [[C]]
+; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[TMP0]]
+; CHECK-NEXT: [[TMP2:%.*]] = select i1 true, i1 [[TMP1]], i1 false
+; CHECK-NEXT: [[TMP3:%.*]] = xor i1 true, [[C2]]
+; CHECK-NEXT: [[TMP4:%.*]] = freeze i1 [[TMP3]]
+; CHECK-NEXT: [[TMP5:%.*]] = select i1 [[TMP2]], i1 [[TMP4]], i1 false
+; CHECK-NEXT: br i1 [[TMP5]], label [[ENTRY_SPLIT:%.*]], label [[ENTRY_SPLIT_NONCHR:%.*]], !prof [[PROF30:![0-9]+]]
+; CHECK: entry.split:
+; CHECK-NEXT: switch i8 0, label [[BB1:%.*]] [
+; CHECK-NEXT: i8 1, label [[BB2:%.*]]
+; CHECK-NEXT: i8 2, label [[BB3:%.*]]
+; CHECK-NEXT: ]
+; CHECK: bb1:
+; CHECK-NEXT: [[SELECT:%.*]] = select i1 false, i32 0, i32 1, !prof [[PROF31:![0-9]+]]
+; CHECK-NEXT: br label [[EXIT:%.*]]
+; CHECK: bb2:
+; CHECK-NEXT: [[SELECT3:%.*]] = select i1 false, i32 0, i32 1, !prof [[PROF32:![0-9]+]]
+; CHECK-NEXT: br label [[EXIT]]
+; CHECK: dead:
+; CHECK-NEXT: br label [[BB3]]
+; CHECK: bb3:
+; CHECK-NEXT: [[PHI:%.*]] = phi i64 [ 0, [[DEAD:%.*]] ], [ 1, [[ENTRY_SPLIT]] ]
+; CHECK-NEXT: br label [[EXIT]]
+; CHECK: entry.split.nonchr:
+; CHECK-NEXT: switch i8 0, label [[BB1_NONCHR:%.*]] [
+; CHECK-NEXT: i8 1, label [[BB2_NONCHR:%.*]]
+; CHECK-NEXT: i8 2, label [[BB3_NONCHR:%.*]]
+; CHECK-NEXT: ]
+; CHECK: bb1.nonchr:
+; CHECK-NEXT: [[SELECT_NONCHR:%.*]] = select i1 [[C]], i32 0, i32 1, !prof [[PROF31]]
+; CHECK-NEXT: br label [[EXIT]]
+; CHECK: bb2.nonchr:
+; CHECK-NEXT: [[SELECT3_NONCHR:%.*]] = select i1 [[C2]], i32 0, i32 1, !prof [[PROF32]]
+; CHECK-NEXT: br label [[EXIT]]
+; CHECK: bb3.nonchr:
+; CHECK-NEXT: [[PHI_NONCHR:%.*]] = phi i64 [ 1, [[ENTRY_SPLIT_NONCHR]] ]
+; CHECK-NEXT: br label [[EXIT]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ switch i8 0, label %bb1 [
+ i8 1, label %bb2
+ i8 2, label %bb3
+ ]
+
+bb1: ; preds = %entry
+ %select = select i1 %c, i32 0, i32 1, !prof !30
+ br label %exit
+
+bb2: ; preds = %entry
+ %select3 = select i1 %c2, i32 0, i32 1, !prof !31
+ br label %exit
+
+dead: ; No predecessors!
+ br label %bb3
+
+bb3: ; preds = %dead, %entry
+ %phi = phi i64 [ 0, %dead ], [ 1, %entry ]
+ br label %exit
+
+exit: ; preds = %bb3, %bb2, %bb1
+ ret void
+}
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"ProfileSummary", !1}
+!1 = !{!2, !3, !4, !5, !6, !7, !8, !9, !10, !11}
+!2 = !{!"ProfileFormat", !"InstrProf"}
+!3 = !{!"TotalCount", i64 597326977313}
+!4 = !{!"MaxCount", i64 12561793713}
+!5 = !{!"MaxInternalCount", i64 2509052618}
+!6 = !{!"MaxFunctionCount", i64 12561793713}
+!7 = !{!"NumCounts", i64 1694881}
+!8 = !{!"NumFunctions", i64 129214}
+!9 = !{!"IsPartialProfile", i64 0}
+!10 = !{!"PartialProfileRatio", double 0.000000e+00}
+!11 = !{!"DetailedSummary", !12}
+!12 = !{!13, !14, !15, !16, !17, !18, !19, !20, !21, !22, !23, !24, !25, !26, !27, !28}
+!13 = !{i32 10000, i64 12561793713, i32 1}
+!14 = !{i32 100000, i64 1733566697, i32 20}
+!15 = !{i32 200000, i64 820928443, i32 71}
+!16 = !{i32 300000, i64 404967336, i32 182}
+!17 = !{i32 400000, i64 233162193, i32 376}
+!18 = !{i32 500000, i64 120552435, i32 741}
+!19 = !{i32 600000, i64 69388652, i32 1402}
+!20 = !{i32 700000, i64 33926336, i32 2643}
+!21 = !{i32 800000, i64 15635940, i32 5288}
+!22 = !{i32 900000, i64 5547105, i32 11637}
+!23 = !{i32 950000, i64 2224405, i32 20074}
+!24 = !{i32 990000, i64 359838, i32 44778}
+!25 = !{i32 999000, i64 37485, i32 81744}
+!26 = !{i32 999900, i64 3465, i32 119656}
+!27 = !{i32 999990, i64 529, i32 155440}
+!28 = !{i32 999999, i64 70, i32 178344}
+!29 = !{!"function_entry_count", i64 33781183}
+!30 = !{!"branch_weights", i32 0, i32 9263770}
+!31 = !{!"branch_weights", i32 0, i32 634318}
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