[llvm] Revert "[CVP] Check whether the default case is reachable (#79993)" (PR #81585)
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Tue Feb 13 01:02:21 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: Yingwei Zheng (dtcxzyw)
<details>
<summary>Changes</summary>
This reverts commit a034e65e972175a2465deacb8c78bc7efc99bd23.
Some protobuf users reported that this patch caused a significant compile-time regression because `TailDuplicator` works poorly with a specific pattern.
We will reland it once the codegen issue is fixed.
---
Full diff: https://github.com/llvm/llvm-project/pull/81585.diff
3 Files Affected:
- (modified) llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp (-34)
- (modified) llvm/test/Transforms/CorrelatedValuePropagation/basic.ll (+5-6)
- (removed) llvm/test/Transforms/CorrelatedValuePropagation/switch.ll (-301)
``````````diff
diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 24e1677bf64342..9235850de92f3e 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -371,7 +371,6 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI,
{ // Scope for SwitchInstProfUpdateWrapper. It must not live during
// ConstantFoldTerminator() as the underlying SwitchInst can be changed.
SwitchInstProfUpdateWrapper SI(*I);
- unsigned ReachableCaseCount = 0;
for (auto CI = SI->case_begin(), CE = SI->case_end(); CI != CE;) {
ConstantInt *Case = CI->getCaseValue();
@@ -408,33 +407,6 @@ static bool processSwitch(SwitchInst *I, LazyValueInfo *LVI,
// Increment the case iterator since we didn't delete it.
++CI;
- ++ReachableCaseCount;
- }
-
- BasicBlock *DefaultDest = SI->getDefaultDest();
- if (ReachableCaseCount > 1 &&
- !isa<UnreachableInst>(DefaultDest->getFirstNonPHIOrDbg())) {
- ConstantRange CR = LVI->getConstantRangeAtUse(I->getOperandUse(0),
- /*UndefAllowed*/ false);
- // The default dest is unreachable if all cases are covered.
- if (!CR.isSizeLargerThan(ReachableCaseCount)) {
- BasicBlock *NewUnreachableBB =
- BasicBlock::Create(BB->getContext(), "default.unreachable",
- BB->getParent(), DefaultDest);
- new UnreachableInst(BB->getContext(), NewUnreachableBB);
-
- DefaultDest->removePredecessor(BB);
- SI->setDefaultDest(NewUnreachableBB);
-
- if (SuccessorsCount[DefaultDest] == 1)
- DTU.applyUpdatesPermissive(
- {{DominatorTree::Delete, BB, DefaultDest}});
- DTU.applyUpdatesPermissive(
- {{DominatorTree::Insert, BB, NewUnreachableBB}});
-
- ++NumDeadCases;
- Changed = true;
- }
}
}
@@ -1255,12 +1227,6 @@ CorrelatedValuePropagationPass::run(Function &F, FunctionAnalysisManager &AM) {
if (!Changed) {
PA = PreservedAnalyses::all();
} else {
-#if defined(EXPENSIVE_CHECKS)
- assert(DT->verify(DominatorTree::VerificationLevel::Full));
-#else
- assert(DT->verify(DominatorTree::VerificationLevel::Fast));
-#endif // EXPENSIVE_CHECKS
-
PA.preserve<DominatorTreeAnalysis>();
PA.preserve<LazyValueAnalysis>();
}
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
index 93ed008022e211..8dce9ef9fa4350 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/basic.ll
@@ -442,7 +442,7 @@ define i32 @switch_range(i32 %cond) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[S:%.*]] = urem i32 [[COND:%.*]], 3
; CHECK-NEXT: [[S1:%.*]] = add nuw nsw i32 [[S]], 1
-; CHECK-NEXT: switch i32 [[S1]], label [[DEFAULT_UNREACHABLE:%.*]] [
+; CHECK-NEXT: switch i32 [[S1]], label [[UNREACHABLE:%.*]] [
; CHECK-NEXT: i32 1, label [[EXIT1:%.*]]
; CHECK-NEXT: i32 2, label [[EXIT2:%.*]]
; CHECK-NEXT: i32 3, label [[EXIT1]]
@@ -451,8 +451,6 @@ define i32 @switch_range(i32 %cond) {
; CHECK-NEXT: ret i32 1
; CHECK: exit2:
; CHECK-NEXT: ret i32 2
-; CHECK: default.unreachable:
-; CHECK-NEXT: unreachable
; CHECK: unreachable:
; CHECK-NEXT: ret i32 0
;
@@ -515,9 +513,10 @@ define i8 @switch_defaultdest_multipleuse(i8 %t0) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[O:%.*]] = or i8 [[T0:%.*]], 1
; CHECK-NEXT: [[R:%.*]] = srem i8 1, [[O]]
-; CHECK-NEXT: br label [[EXIT:%.*]]
-; CHECK: default.unreachable:
-; CHECK-NEXT: unreachable
+; CHECK-NEXT: switch i8 [[R]], label [[EXIT:%.*]] [
+; CHECK-NEXT: i8 0, label [[EXIT]]
+; CHECK-NEXT: i8 1, label [[EXIT]]
+; CHECK-NEXT: ]
; CHECK: exit:
; CHECK-NEXT: ret i8 0
;
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/switch.ll b/llvm/test/Transforms/CorrelatedValuePropagation/switch.ll
deleted file mode 100644
index a0794d5efe9320..00000000000000
--- a/llvm/test/Transforms/CorrelatedValuePropagation/switch.ll
+++ /dev/null
@@ -1,301 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
-; RUN: opt < %s -passes=correlated-propagation -S | FileCheck %s
-
-define i32 @test_unreachable_default(i32 noundef %num) {
-; CHECK-LABEL: define i32 @test_unreachable_default(
-; CHECK-SAME: i32 noundef [[NUM:%.*]]) {
-; CHECK-NEXT: entry:
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[NUM]], -120
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[SUB]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2
-; CHECK-NEXT: switch i32 [[COND]], label [[DEFAULT_UNREACHABLE:%.*]] [
-; CHECK-NEXT: i32 0, label [[SW_BB:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB4:%.*]]
-; CHECK-NEXT: ]
-; CHECK: sw.bb:
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @call0()
-; CHECK-NEXT: br label [[CLEANUP:%.*]]
-; CHECK: sw.bb2:
-; CHECK-NEXT: [[CALL3:%.*]] = call i32 @call1()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.bb4:
-; CHECK-NEXT: [[CALL5:%.*]] = call i32 @call2()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: default.unreachable:
-; CHECK-NEXT: unreachable
-; CHECK: sw.default:
-; CHECK-NEXT: [[CALL6:%.*]] = call i32 @call3()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: cleanup:
-; CHECK-NEXT: [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT:%.*]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]
-; CHECK-NEXT: ret i32 [[RETVAL_0]]
-;
-entry:
- %sub = add i32 %num, -120
- %cmp = icmp ult i32 %sub, 3
- %cond = select i1 %cmp, i32 %sub, i32 2
- switch i32 %cond, label %sw.default [
- i32 0, label %sw.bb
- i32 1, label %sw.bb2
- i32 2, label %sw.bb4
- ]
-
-sw.bb:
- %call = call i32 @call0()
- br label %cleanup
-
-sw.bb2:
- %call3 = call i32 @call1()
- br label %cleanup
-
-sw.bb4:
- %call5 = call i32 @call2()
- br label %cleanup
-
-sw.default:
- %call6 = call i32 @call3()
- br label %cleanup
-
-cleanup:
- %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]
- ret i32 %retval.0
-}
-
-define i32 @test_unreachable_default_shared_edge(i32 noundef %num) {
-; CHECK-LABEL: define i32 @test_unreachable_default_shared_edge(
-; CHECK-SAME: i32 noundef [[NUM:%.*]]) {
-; CHECK-NEXT: entry:
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[NUM]], -120
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[SUB]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2
-; CHECK-NEXT: switch i32 [[COND]], label [[DEFAULT_UNREACHABLE:%.*]] [
-; CHECK-NEXT: i32 0, label [[SW_BB:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB4:%.*]]
-; CHECK-NEXT: ]
-; CHECK: sw.bb:
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @call0()
-; CHECK-NEXT: br label [[CLEANUP:%.*]]
-; CHECK: sw.bb2:
-; CHECK-NEXT: [[CALL3:%.*]] = call i32 @call1()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: default.unreachable:
-; CHECK-NEXT: unreachable
-; CHECK: sw.bb4:
-; CHECK-NEXT: [[CALL5:%.*]] = call i32 @call4(i32 [[SUB]])
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: cleanup:
-; CHECK-NEXT: [[RETVAL_0:%.*]] = phi i32 [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]
-; CHECK-NEXT: ret i32 [[RETVAL_0]]
-;
-entry:
- %sub = add i32 %num, -120
- %cmp = icmp ult i32 %sub, 3
- %cond = select i1 %cmp, i32 %sub, i32 2
- switch i32 %cond, label %sw.bb4 [
- i32 0, label %sw.bb
- i32 1, label %sw.bb2
- i32 2, label %sw.bb4
- ]
-
-sw.bb:
- %call = call i32 @call0()
- br label %cleanup
-
-sw.bb2:
- %call3 = call i32 @call1()
- br label %cleanup
-
-sw.bb4:
- %val = phi i32 [ %sub, %entry ], [ %sub, %entry ]
- %call5 = call i32 @call4(i32 %val)
- br label %cleanup
-
-cleanup:
- %retval.0 = phi i32 [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]
- ret i32 %retval.0
-}
-
-; Negative tests
-
-define i32 @test_reachable_default(i32 noundef %num) {
-; CHECK-LABEL: define i32 @test_reachable_default(
-; CHECK-SAME: i32 noundef [[NUM:%.*]]) {
-; CHECK-NEXT: entry:
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[NUM]], -120
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[SUB]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 4
-; CHECK-NEXT: switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[SW_BB:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB4:%.*]]
-; CHECK-NEXT: ]
-; CHECK: sw.bb:
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @call0()
-; CHECK-NEXT: br label [[CLEANUP:%.*]]
-; CHECK: sw.bb2:
-; CHECK-NEXT: [[CALL3:%.*]] = call i32 @call1()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.bb4:
-; CHECK-NEXT: [[CALL5:%.*]] = call i32 @call2()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.default:
-; CHECK-NEXT: [[CALL6:%.*]] = call i32 @call3()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: cleanup:
-; CHECK-NEXT: [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]
-; CHECK-NEXT: ret i32 [[RETVAL_0]]
-;
-entry:
- %sub = add i32 %num, -120
- %cmp = icmp ult i32 %sub, 3
- %cond = select i1 %cmp, i32 %sub, i32 4
- switch i32 %cond, label %sw.default [
- i32 0, label %sw.bb
- i32 1, label %sw.bb2
- i32 2, label %sw.bb4
- ]
-
-sw.bb:
- %call = call i32 @call0()
- br label %cleanup
-
-sw.bb2:
- %call3 = call i32 @call1()
- br label %cleanup
-
-sw.bb4:
- %call5 = call i32 @call2()
- br label %cleanup
-
-sw.default:
- %call6 = call i32 @call3()
- br label %cleanup
-
-cleanup:
- %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]
- ret i32 %retval.0
-}
-
-define i32 @test_unreachable_default_cond_may_be_undef(i32 %num) {
-; CHECK-LABEL: define i32 @test_unreachable_default_cond_may_be_undef(
-; CHECK-SAME: i32 [[NUM:%.*]]) {
-; CHECK-NEXT: entry:
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[NUM]], -120
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[SUB]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2
-; CHECK-NEXT: switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[SW_BB:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB4:%.*]]
-; CHECK-NEXT: ]
-; CHECK: sw.bb:
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @call0()
-; CHECK-NEXT: br label [[CLEANUP:%.*]]
-; CHECK: sw.bb2:
-; CHECK-NEXT: [[CALL3:%.*]] = call i32 @call1()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.bb4:
-; CHECK-NEXT: [[CALL5:%.*]] = call i32 @call2()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.default:
-; CHECK-NEXT: [[CALL6:%.*]] = call i32 @call3()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: cleanup:
-; CHECK-NEXT: [[RETVAL_0:%.*]] = phi i32 [ [[CALL6]], [[SW_DEFAULT]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]
-; CHECK-NEXT: ret i32 [[RETVAL_0]]
-;
-entry:
- %sub = add i32 %num, -120
- %cmp = icmp ult i32 %sub, 3
- %cond = select i1 %cmp, i32 %sub, i32 2
- switch i32 %cond, label %sw.default [
- i32 0, label %sw.bb
- i32 1, label %sw.bb2
- i32 2, label %sw.bb4
- ]
-
-sw.bb:
- %call = call i32 @call0()
- br label %cleanup
-
-sw.bb2:
- %call3 = call i32 @call1()
- br label %cleanup
-
-sw.bb4:
- %call5 = call i32 @call2()
- br label %cleanup
-
-sw.default:
- %call6 = call i32 @call3()
- br label %cleanup
-
-cleanup:
- %retval.0 = phi i32 [ %call6, %sw.default ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]
- ret i32 %retval.0
-}
-
-define i32 @test_default_is_already_unreachable(i32 %num) {
-; CHECK-LABEL: define i32 @test_default_is_already_unreachable(
-; CHECK-SAME: i32 [[NUM:%.*]]) {
-; CHECK-NEXT: entry:
-; CHECK-NEXT: [[SUB:%.*]] = add i32 [[NUM]], -120
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[SUB]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB]], i32 2
-; CHECK-NEXT: switch i32 [[COND]], label [[SW_DEFAULT:%.*]] [
-; CHECK-NEXT: i32 0, label [[SW_BB:%.*]]
-; CHECK-NEXT: i32 1, label [[SW_BB2:%.*]]
-; CHECK-NEXT: i32 2, label [[SW_BB4:%.*]]
-; CHECK-NEXT: ]
-; CHECK: sw.bb:
-; CHECK-NEXT: [[CALL:%.*]] = call i32 @call0()
-; CHECK-NEXT: br label [[CLEANUP:%.*]]
-; CHECK: sw.bb2:
-; CHECK-NEXT: [[CALL3:%.*]] = call i32 @call1()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.bb4:
-; CHECK-NEXT: [[CALL5:%.*]] = call i32 @call2()
-; CHECK-NEXT: br label [[CLEANUP]]
-; CHECK: sw.default:
-; CHECK-NEXT: unreachable
-; CHECK: cleanup:
-; CHECK-NEXT: [[RETVAL_0:%.*]] = phi i32 [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ]
-; CHECK-NEXT: ret i32 [[RETVAL_0]]
-;
-entry:
- %sub = add i32 %num, -120
- %cmp = icmp ult i32 %sub, 3
- %cond = select i1 %cmp, i32 %sub, i32 2
- switch i32 %cond, label %sw.default [
- i32 0, label %sw.bb
- i32 1, label %sw.bb2
- i32 2, label %sw.bb4
- ]
-
-sw.bb:
- %call = call i32 @call0()
- br label %cleanup
-
-sw.bb2:
- %call3 = call i32 @call1()
- br label %cleanup
-
-sw.bb4:
- %call5 = call i32 @call2()
- br label %cleanup
-
-sw.default:
- unreachable
-
-cleanup:
- %retval.0 = phi i32 [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ]
- ret i32 %retval.0
-}
-
-declare i32 @call0()
-declare i32 @call1()
-declare i32 @call2()
-declare i32 @call3()
-declare i32 @call4(i32)
``````````
</details>
https://github.com/llvm/llvm-project/pull/81585
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