[clang][analysis] Fix flaky clang/test/Analysis/live-stmts.cpp test (2nd attempt) #127406

steakhal · 2025-02-16T19:10:51Z

In my previous attempt (#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs.

In an EXPENSIVE_CHECKS build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should.
Because of this, I had to revert the previous fix attempt in #127034.

To fix this, I use this time Expr::getID for a stable ID for an Expr.

Hopefully fixes #126619
Hopefully fixes #126804

…2nd attempt) In my previous attempt (llvm#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs. In an `EXPENSIVE_CHECKS` build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should. To fix this, I I use this time `Expr::getID` for a stable ID for an Expr. Hopefully fixes llvm#126619 Hopefully fixes llvm#126804

llvmbot · 2025-02-16T19:11:10Z

@llvm/pr-subscribers-clang-analysis
@llvm/pr-subscribers-clang-static-analyzer-1

@llvm/pr-subscribers-clang

Author: Balazs Benics (steakhal)

Changes

In my previous attempt (#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs.

In an EXPENSIVE_CHECKS build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should.
Because of this, I had to revert the previous fix attempt in #127034.

To fix this, I use this time Expr::getID for a stable ID for an Expr.

Hopefully fixes #126619
Hopefully fixes #126804

Full diff: https://github.com/llvm/llvm-project/pull/127406.diff

2 Files Affected:

(modified) clang/lib/Analysis/LiveVariables.cpp (+4-4)
(modified) clang/test/Analysis/live-stmts.cpp (+22-25)

diff --git a/clang/lib/Analysis/LiveVariables.cpp b/clang/lib/Analysis/LiveVariables.cpp
index af563702b77bf..c7d3451d37cf6 100644
--- a/clang/lib/Analysis/LiveVariables.cpp
+++ b/clang/lib/Analysis/LiveVariables.cpp
@@ -664,18 +664,18 @@ void LiveVariables::dumpExprLiveness(const SourceManager &M) {
 }
 
 void LiveVariablesImpl::dumpExprLiveness(const SourceManager &M) {
-  auto ByBeginLoc = [&M](const Expr *L, const Expr *R) {
-    return M.isBeforeInTranslationUnit(L->getBeginLoc(), R->getBeginLoc());
+  const ASTContext &Ctx = analysisContext.getASTContext();
+  auto ByIDs = [&Ctx](const Expr *L, const Expr *R) {
+    return L->getID(Ctx) < R->getID(Ctx);
   };
 
   // Don't iterate over blockEndsToLiveness directly because it's not sorted.
   for (const CFGBlock *B : *analysisContext.getCFG()) {
-
     llvm::errs() << "\n[ B" << B->getBlockID()
                  << " (live expressions at block exit) ]\n";
     std::vector<const Expr *> LiveExprs;
     llvm::append_range(LiveExprs, blocksEndToLiveness[B].liveExprs);
-    llvm::sort(LiveExprs, ByBeginLoc);
+    llvm::sort(LiveExprs, ByIDs);
     for (const Expr *E : LiveExprs) {
       llvm::errs() << "\n";
       E->dump();
diff --git a/clang/test/Analysis/live-stmts.cpp b/clang/test/Analysis/live-stmts.cpp
index 9cac815e65de1..ca2ff6da8b133 100644
--- a/clang/test/Analysis/live-stmts.cpp
+++ b/clang/test/Analysis/live-stmts.cpp
@@ -1,6 +1,3 @@
-// Disabling this flaky test, see https://github.com/llvm/llvm-project/pull/126913#issuecomment-2655850766
-// UNSUPPORTED: true
-
 // RUN: %clang_analyze_cc1 -w -analyzer-checker=debug.DumpLiveExprs %s 2>&1\
 // RUN:   | FileCheck %s
 
@@ -29,36 +26,36 @@ int testThatDumperWorks(int x, int y, int z) {
 // CHECK-EMPTY:
 // CHECK: [ B2 (live expressions at block exit) ]
 // CHECK-EMPTY:
-// CHECK-NEXT: ImplicitCastExpr {{.*}} <IntegralToBoolean>
-// CHECK-NEXT: `-ImplicitCastExpr {{.*}} <LValueToRValue>
-// CHECK-NEXT:   `-DeclRefExpr {{.*}} 'x' 'int'
-// CHECK-EMPTY:
 // CHECK-NEXT: DeclRefExpr {{.*}} 'y' 'int'
 // CHECK-EMPTY:
 // CHECK-NEXT: DeclRefExpr {{.*}} 'z' 'int'
 // CHECK-EMPTY:
-// CHECK-EMPTY:
-// CHECK: [ B3 (live expressions at block exit) ]
-// CHECK-EMPTY:
 // CHECK-NEXT: ImplicitCastExpr {{.*}} <IntegralToBoolean>
 // CHECK-NEXT: `-ImplicitCastExpr {{.*}} <LValueToRValue>
 // CHECK-NEXT:   `-DeclRefExpr {{.*}} 'x' 'int'
 // CHECK-EMPTY:
-// CHECK-NEXT: DeclRefExpr {{.*}} 'y' 'int'
 // CHECK-EMPTY:
-// CHECK-NEXT: DeclRefExpr {{.*}} 'z' 'int'
+// CHECK: [ B3 (live expressions at block exit) ]
 // CHECK-EMPTY:
+// CHECK-NEXT: DeclRefExpr {{.*}} 'y' 'int'
 // CHECK-EMPTY:
-// CHECK: [ B4 (live expressions at block exit) ]
+// CHECK-NEXT: DeclRefExpr {{.*}} 'z' 'int'
 // CHECK-EMPTY:
 // CHECK-NEXT: ImplicitCastExpr {{.*}} <IntegralToBoolean>
 // CHECK-NEXT: `-ImplicitCastExpr {{.*}} <LValueToRValue>
 // CHECK-NEXT:   `-DeclRefExpr {{.*}} 'x' 'int'
 // CHECK-EMPTY:
+// CHECK-EMPTY:
+// CHECK: [ B4 (live expressions at block exit) ]
+// CHECK-EMPTY:
 // CHECK-NEXT: DeclRefExpr {{.*}} 'y' 'int'
 // CHECK-EMPTY:
 // CHECK-NEXT: DeclRefExpr {{.*}} 'z' 'int'
 // CHECK-EMPTY:
+// CHECK-NEXT: ImplicitCastExpr {{.*}} <IntegralToBoolean>
+// CHECK-NEXT: `-ImplicitCastExpr {{.*}} <LValueToRValue>
+// CHECK-NEXT:   `-DeclRefExpr {{.*}} 'x' 'int'
+// CHECK-EMPTY:
 // CHECK-EMPTY:
 // CHECK: [ B5 (live expressions at block exit) ]
 // CHECK-EMPTY:
@@ -228,15 +225,15 @@ int logicalOpInTernary(bool b) {
 // CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
+// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
+// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
+// CHECK-EMPTY:
 // CHECK: BinaryOperator {{.*}} '_Bool' '||'
 // CHECK: |-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: | `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK: `-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK:   `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
-// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
-// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
-// CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 0
 // CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 1
@@ -247,15 +244,15 @@ int logicalOpInTernary(bool b) {
 // CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
+// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
+// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
+// CHECK-EMPTY:
 // CHECK: BinaryOperator {{.*}} '_Bool' '||'
 // CHECK: |-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: | `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK: `-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK:   `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
-// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
-// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
-// CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 0
 // CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 1
@@ -266,15 +263,15 @@ int logicalOpInTernary(bool b) {
 // CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
+// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
+// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
+// CHECK-EMPTY:
 // CHECK: BinaryOperator {{.*}} '_Bool' '||'
 // CHECK: |-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: | `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK: `-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK:   `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
-// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
-// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
-// CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 0
 // CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 1
@@ -285,15 +282,15 @@ int logicalOpInTernary(bool b) {
 // CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
+// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
+// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
+// CHECK-EMPTY:
 // CHECK: BinaryOperator {{.*}} '_Bool' '||'
 // CHECK: |-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK: | `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK: `-ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
 // CHECK:   `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
 // CHECK-EMPTY:
-// CHECK: ImplicitCastExpr {{.*}} '_Bool' <LValueToRValue>
-// CHECK: `-DeclRefExpr {{.*}} '_Bool' lvalue ParmVar {{.*}} 'b' '_Bool'
-// CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 0
 // CHECK-EMPTY:
 // CHECK: IntegerLiteral {{.*}} 'int' 1

NagyDonat

Let's hope that this fixes the issue.

…2nd attempt) (llvm#127406) In my previous attempt (llvm#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs. In an `EXPENSIVE_CHECKS` build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should. Because of this, I had to revert the previous fix attempt in llvm#127034. To fix this, I use this time `Expr::getID` for a stable ID for an Expr. Hopefully fixes llvm#126619 Hopefully fixes llvm#126804

tstellar · 2025-02-26T01:39:36Z

/cherry-pick f378e52

llvmbot · 2025-02-26T01:44:54Z

Failed to cherry-pick: f378e52

https://github.com/llvm/llvm-project/actions/runs/13534670364

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

tstellar · 2025-05-10T16:29:59Z

Is there interest in backporting this to the release branch? If so, can someone manually create a PR?

…2nd attempt) (llvm#127406) In my previous attempt (llvm#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs. In an `EXPENSIVE_CHECKS` build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should. Because of this, I had to revert the previous fix attempt in llvm#127034. To fix this, I use this time `Expr::getID` for a stable ID for an Expr. Hopefully fixes llvm#126619 Hopefully fixes llvm#126804 (cherry picked from commit f378e52)

steakhal · 2025-05-12T17:42:22Z

Is there interest in backporting this to the release branch? If so, can someone manually create a PR?

Thanks for the heads up. Here is the manual backport: #139591 @tstellar

…2nd attempt) (llvm#127406) In my previous attempt (llvm#126913) of fixing the flaky case was on a good track when I used the begin locations as a stable ordering. However, I forgot to consider the case when the begin locations are the same among the Exprs. In an `EXPENSIVE_CHECKS` build, arrays are randomly shuffled prior to sorting them. This exposed the flaky behavior much more often basically breaking the "stability" of the vector - as it should. Because of this, I had to revert the previous fix attempt in llvm#127034. To fix this, I use this time `Expr::getID` for a stable ID for an Expr. Hopefully fixes llvm#126619 Hopefully fixes llvm#126804 (cherry picked from commit f378e52)

steakhal added clang Clang issues not falling into any other category clang:static analyzer clang:analysis labels Feb 16, 2025

steakhal requested review from Xazax-hun and NagyDonat February 16, 2025 19:10

NagyDonat approved these changes Feb 17, 2025

View reviewed changes

steakhal merged commit f378e52 into llvm:main Feb 17, 2025
12 checks passed

steakhal deleted the bb/fix-flaky-live-stmts-test branch February 17, 2025 10:13

tstellar added this to the LLVM 20.X Release milestone Feb 26, 2025

llvmbot added the release:cherry-pick-failed label Feb 26, 2025

tstellar moved this from Needs Triage to Needs Pull Request in LLVM Release Status Mar 11, 2025

steakhal mentioned this pull request May 12, 2025

[clang][analysis] Fix flaky clang/test/Analysis/live-stmts.cpp test (2nd attempt) (#127406) #139591

Merged

tstellar moved this from Needs Backport PR to Done in LLVM Release Status May 13, 2025

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[clang][analysis] Fix flaky clang/test/Analysis/live-stmts.cpp test (2nd attempt) #127406

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[clang][analysis] Fix flaky clang/test/Analysis/live-stmts.cpp test (2nd attempt) #127406

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