[clang] c68baa7 - [clang] Fix incorrect constant folding of `if consteval`
Corentin Jabot via cfe-commits
cfe-commits at lists.llvm.org
Sun Jul 24 07:18:17 PDT 2022
Author: Corentin Jabot
Date: 2022-07-24T16:18:12+02:00
New Revision: c68baa73eb437556cd8abe40902182a6034930ac
URL: https://github.com/llvm/llvm-project/commit/c68baa73eb437556cd8abe40902182a6034930ac
DIFF: https://github.com/llvm/llvm-project/commit/c68baa73eb437556cd8abe40902182a6034930ac.diff
LOG: [clang] Fix incorrect constant folding of `if consteval`
Fixes https://github.com/llvm/llvm-project/issues/55638.
`if consteval` was evaluated incorrectly when in a
non-constant context that could be constant-folded.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D130437
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/lib/AST/ExprConstant.cpp
clang/test/CodeGenCXX/cxx2b-consteval-if.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index ac6c5bb543121..af64152666757 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -194,6 +194,8 @@ Bug Fixes
move assignment operator. Fixes `Issue 56456 <https://github.com/llvm/llvm-project/issues/56456>`_.
- Fixed a crash when a variable with a bool enum type that has no definition
used in comparison operators. Fixes `Issue 56560 <https://github.com/llvm/llvm-project/issues/56560>`_.
+- Fix that ``if consteval`` could evaluate to ``true`` at runtime because it was incorrectly
+ constant folded. Fixes `Issue 55638 <https://github.com/llvm/llvm-project/issues/55638>`_.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 6ffb65d8e71d3..9d92c848ccb84 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -5266,10 +5266,14 @@ static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
}
}
bool Cond;
- if (IS->isConsteval())
+ if (IS->isConsteval()) {
Cond = IS->isNonNegatedConsteval();
- else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
- Cond))
+ // If we are not in a constant context, if consteval should not evaluate
+ // to true.
+ if (!Info.InConstantContext)
+ Cond = !Cond;
+ } else if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(),
+ Cond))
return ESR_Failed;
if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
diff --git a/clang/test/CodeGenCXX/cxx2b-consteval-if.cpp b/clang/test/CodeGenCXX/cxx2b-consteval-if.cpp
index 2e38ce0e63639..a69a2271f661b 100644
--- a/clang/test/CodeGenCXX/cxx2b-consteval-if.cpp
+++ b/clang/test/CodeGenCXX/cxx2b-consteval-if.cpp
@@ -26,3 +26,30 @@ constexpr void f() {
void g() {
f();
}
+
+namespace GH55638 {
+
+constexpr bool is_constant_evaluated() noexcept {
+ if consteval { return true; } else { return false; }
+}
+
+constexpr int compiletime(int) {
+ return 2;
+}
+
+constexpr int runtime(int) {
+ return 1;
+}
+
+constexpr int test(int x) {
+ if(is_constant_evaluated())
+ return compiletime(x); // CHECK-NOT: call {{.*}}compiletime
+ return runtime(x); // CHECK: call {{.*}}runtime
+}
+
+int f(int x) {
+ x = test(x);
+ return x;
+}
+
+}
More information about the cfe-commits
mailing list