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[KeyInstr][Clang] Switch stmt atom

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This patch is part of a stack that teaches Clang to generate Key Instructions
metadata for C and C++.

The Key Instructions project is introduced, including a "quick summary" section
at the top which adds context for this PR, here:
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.

The Clang-side work is demoed here:
https://github.com/llvm/llvm-project/pull/130943
This commit is contained in:
Orlando Cazalet-Hyams 2025-04-03 18:43:56 +01:00
parent 98ea64f7a1
commit eeee08d6d9
2 changed files with 53 additions and 0 deletions
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2
clang/lib/CodeGen/CGStmt.cpp
View File

@ -2276,6 +2276,8 @@ void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
// failure.
llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
addInstToNewSourceAtom(SwitchInsn, CondV);
if (HLSLControlFlowAttr != HLSLControlFlowHintAttr::SpellingNotCalculated) {
llvm::MDBuilder MDHelper(CGM.getLLVMContext());
llvm::ConstantInt *BranchHintConstant =

51
clang/test/KeyInstructions/switch.c Normal file
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@ -0,0 +1,51 @@
// RUN: %clang -gkey-instructions -x c++ -std=c++17 %s -gmlt -S -emit-llvm -o - \
// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank --check-prefixes=CHECK,CHECK-CXX
// RUN: %clang -gkey-instructions -x c %s -gmlt -S -emit-llvm -o - \
// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
int g;
void a(int A, int B) {
// CHECK: entry:
// The load gets associated with the branch rather than the store.
// FIXME: Is that the best thing to do?
// CHECK: %0 = load i32, ptr %A.addr{{.*}}, !dbg [[G2R2:!.*]]
// CHECK: store i32 %0, ptr @g{{.*}}, !dbg [[G1R1:!.*]]
// CHECK: switch i32 %0, label %{{.*}} [
// CHECK: i32 0, label %sw.bb
// CHECK: i32 1, label %sw.bb1
// CHECK: ], !dbg [[G2R1:!.*]]
switch ((g = A)) {
case 0: break;
case 1: {
// CHECK: sw.bb1:
// CHECK: %1 = load i32, ptr %B.addr{{.*}}, !dbg [[G3R2:!.*]]
// CHECK: switch i32 %1, label %{{.*}} [
// CHECK: i32 0, label %sw.bb2
// CHECK: ], !dbg [[G3R1:!.*]]
switch ((B)) {
case 0: {
// Test that assignments in constant-folded switches don't go missing.
// CHECK-CXX: sw.bb2:
// CHECK-CXX: store i32 1, ptr %C{{.*}}, !dbg [[G4R1:!.*]]
#ifdef __cplusplus
switch (const int C = 1; C) {
case 0: break;
case 1: break;
default: break;
}
#endif
} break;
default: break;
}
} break;
default: break;
}
}
// CHECK: [[G2R2]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
// CHECK: [[G3R2]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 2)
// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
// CHECK-CXX: [[G4R1]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)