From d791de0e25e13cd8ae066e6f0fa03b384502b02e Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Tue, 12 Apr 2022 17:13:06 -0700 Subject: [PATCH] Restrict lvalue-to-rvalue conversions in CGExprConstant. We were generating wrong code for cxx20-consteval-crash.cpp: instead of loading a value of a variable, we were using its address as the initializer. Found while adding code to verify the size of constant initializers. Differential Revision: https://reviews.llvm.org/D123648 --- clang/lib/CodeGen/CGExprConstant.cpp | 11 ++++++++++- clang/test/CodeGenCXX/cxx20-consteval-crash.cpp | 4 ++-- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp index 6397ff5..92122f0 100644 --- a/clang/lib/CodeGen/CGExprConstant.cpp +++ b/clang/lib/CodeGen/CGExprConstant.cpp @@ -1092,7 +1092,16 @@ public: destAS, destTy); } - case CK_LValueToRValue: + case CK_LValueToRValue: { + // We don't really support doing lvalue-to-rvalue conversions here; any + // interesting conversions should be done in Evaluate(). But as a + // special case, allow compound literals to support the gcc extension + // allowing "struct x {int x;} x = (struct x) {};". + if (auto *E = dyn_cast(subExpr->IgnoreParens())) + return Visit(E->getInitializer(), destType); + return nullptr; + } + case CK_AtomicToNonAtomic: case CK_NonAtomicToAtomic: case CK_NoOp: diff --git a/clang/test/CodeGenCXX/cxx20-consteval-crash.cpp b/clang/test/CodeGenCXX/cxx20-consteval-crash.cpp index c8ca6a56..c7f0377 100644 --- a/clang/test/CodeGenCXX/cxx20-consteval-crash.cpp +++ b/clang/test/CodeGenCXX/cxx20-consteval-crash.cpp @@ -9,7 +9,7 @@ auto x2 = X(); // CHECK: @_ZN7PR507872x_E = external global i32, align 4 // CHECK-NEXT: @_ZN7PR507872x1E = constant i32* @_ZN7PR507872x_E, align 8 -// CHECK-NEXT: @_ZN7PR507872x2E = global i32* @_ZN7PR507872x_E, align 4 +// CHECK-NEXT: @_ZN7PR507872x2E = global i32 0, align 4 } namespace PR51484 { @@ -18,7 +18,7 @@ struct X { int val; }; consteval X g() { return {0}; } void f() { g(); } -// CHECK: define dso_local void @_ZN7PR514841fEv() #0 { +// CHECK: define dso_local void @_ZN7PR514841fEv() #1 { // CHECK: entry: // CHECK-NOT: call i32 @_ZN7PR514841gEv() // CHECK: ret void -- 2.7.4