Author: Orlando Cazalet-Hyams Date: 2025-05-23T14:31:18+01:00 New Revision: 189d5dad364a402c79901cea2c9cdac03b7c5560
URL: https://github.com/llvm/llvm-project/commit/189d5dad364a402c79901cea2c9cdac03b7c5560 DIFF: https://github.com/llvm/llvm-project/commit/189d5dad364a402c79901cea2c9cdac03b7c5560.diff LOG: [KeyInstr][Clang] Do stmt atom (#134644) See test comment for possible future improvement. This patch is part of a stack that teaches Clang to generate Key Instructions metadata for C and C++. RFC: https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668 The feature is only functional in LLVM if LLVM is built with CMake flag LLVM_EXPERIMENTAL_KEY_INSTRUCTIONs. Eventually that flag will be removed. Added: clang/test/DebugInfo/KeyInstructions/do.c Modified: clang/lib/CodeGen/CGStmt.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp index 3562b4ea22a24..ca1e6522ad564 100644 --- a/clang/lib/CodeGen/CGStmt.cpp +++ b/clang/lib/CodeGen/CGStmt.cpp @@ -1242,9 +1242,18 @@ void CodeGenFunction::EmitDoStmt(const DoStmt &S, // As long as the condition is true, iterate the loop. if (EmitBoolCondBranch) { uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount; - Builder.CreateCondBr( + auto *I = Builder.CreateCondBr( BoolCondVal, LoopBody, LoopExit.getBlock(), createProfileWeightsForLoop(S.getCond(), BackedgeCount)); + + // Key Instructions: Emit the condition and branch as separate source + // location atoms otherwise we may omit a step onto the loop condition in + // favour of the closing brace. + // FIXME: We could have the branch as the backup location for the condition, + // which would probably be a better experience (no jumping to the brace). + if (auto *CondI = dyn_cast<llvm::Instruction>(BoolCondVal)) + addInstToNewSourceAtom(CondI, nullptr); + addInstToNewSourceAtom(I, nullptr); } LoopStack.pop(); diff --git a/clang/test/DebugInfo/KeyInstructions/do.c b/clang/test/DebugInfo/KeyInstructions/do.c new file mode 100644 index 0000000000000..f3b2bb465cae8 --- /dev/null +++ b/clang/test/DebugInfo/KeyInstructions/do.c @@ -0,0 +1,33 @@ +// RUN: %clang_cc1 -gkey-instructions -x c++ -std=c++17 %s -debug-info-kind=line-tables-only -emit-llvm -o - \ +// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank + +// RUN: %clang_cc1 -gkey-instructions -x c %s -debug-info-kind=line-tables-only -emit-llvm -o - \ +// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank + +// Perennial question: should the `dec` be in its own source atom or not +// (currently it is). + +// Another question - we've made the cmp and br separate source atoms for +// now, to match existing behaviour in this case: +// 1. do { +// 2. something(); +// 3. } +// 4. while (--A); +// Non key instruction behaviour is: 2, 4[, 3, 2, 4]+ +// The cond br is associated with the brace on line 3 and the cmp is line 4; +// if they were in the same atom group we'd step just: 2, 3[, 2, 3]+ +// FIXME: We could arguably improve the behaviour by making them the same +// group but having the cmp higher precedence, resulting in: 2, 4[, 2, 4]+. + +void a(int A) { +// CHECK: %dec = add nsw i32 %0, -1, !dbg [[G1R2:!.*]] +// CHECK: store i32 %dec, ptr %A.addr{{.*}}, !dbg [[G1R1:!.*]] +// CHECK: %tobool = icmp ne i32 %dec, 0, !dbg [[G2R1:!.*]] +// CHECK: br i1 %tobool, label %do.body, label %do.end, !dbg [[G3R1:!.*]], !llvm.loop + do { } while (--A); +} + +// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2) +// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1) +// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1) +// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1) _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
