Author: Yingwei Zheng Date: 2024-09-04T13:36:32+08:00 New Revision: c94bd96c277e0b48e198fdc831bb576d9a04aced
URL: https://github.com/llvm/llvm-project/commit/c94bd96c277e0b48e198fdc831bb576d9a04aced DIFF: https://github.com/llvm/llvm-project/commit/c94bd96c277e0b48e198fdc831bb576d9a04aced.diff LOG: [Clang][CodeGen] Don't emit assumptions if current block is unreachable. (#106936) Fixes https://github.com/llvm/llvm-project/issues/106898. When emitting an infinite loop, clang codegen will delete the whole block and leave builder's current block as nullptr: https://github.com/llvm/llvm-project/blob/837ee5b46a5f7f898f0de7e46a19600b896a0a1f/clang/lib/CodeGen/CGStmt.cpp#L597-L600 Then clang will create `zext (icmp slt %a, %b)` without parent block for `a < b`. It will crash here: https://github.com/llvm/llvm-project/blob/837ee5b46a5f7f898f0de7e46a19600b896a0a1f/clang/lib/CodeGen/CGExprScalar.cpp#L416-L420 Even if we disabled this optimization, it still crashes in `Builder.CreateAssumption`: https://github.com/llvm/llvm-project/blob/837ee5b46a5f7f898f0de7e46a19600b896a0a1f/llvm/lib/IR/IRBuilder.cpp#L551-L561 This patch disables assumptions emission if current block is null. Added: Modified: clang/lib/CodeGen/CGStmt.cpp clang/test/SemaCXX/cxx23-assume.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp index 7158a06e6bc3b3..b138c87a853495 100644 --- a/clang/lib/CodeGen/CGStmt.cpp +++ b/clang/lib/CodeGen/CGStmt.cpp @@ -752,7 +752,7 @@ void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) { } break; case attr::CXXAssume: { const Expr *Assumption = cast<CXXAssumeAttr>(A)->getAssumption(); - if (getLangOpts().CXXAssumptions && + if (getLangOpts().CXXAssumptions && Builder.GetInsertBlock() && !Assumption->HasSideEffects(getContext())) { llvm::Value *AssumptionVal = EvaluateExprAsBool(Assumption); Builder.CreateAssumption(AssumptionVal); diff --git a/clang/test/SemaCXX/cxx23-assume.cpp b/clang/test/SemaCXX/cxx23-assume.cpp index 9138501d726dd6..eeae59daea3f70 100644 --- a/clang/test/SemaCXX/cxx23-assume.cpp +++ b/clang/test/SemaCXX/cxx23-assume.cpp @@ -158,3 +158,12 @@ foo (int x, int y) return x + y; } } + +// Do not crash when assumptions are unreachable. +namespace gh106898 { +int foo () { + while(1); + int a = 0, b = 1; + __attribute__((assume (a < b))); +} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
