[DebugInfo][InstCombine] Propagate DILocation when noop-ing invoke

[SLTozer]

In InstCombine we may decide that an alloc is removable, and the alloc fn is called by an InvokeInst, we replace that InvokeInst with a invoke of a noop intrinsic; this patch has us also copy the original invoke's DILocation to the new noop invoke.

Found using #107279.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-debuginfo

Author: Stephen Tozer (SLTozer)

Changes

In InstCombine we may decide that an alloc is removable, and the alloc fn is called by an InvokeInst, we replace that InvokeInst with a invoke of a noop intrinsic; this patch has us also copy the original invoke's DILocation to the new noop invoke.

Found using #107279.

---

Full diff: https://github.com/llvm/llvm-project/pull/134678.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/InstCombine/InstructionCombining.cpp (+3-2)
• (added) llvm/test/Transforms/InstCombine/debuginfo-invoke.ll (+51)

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 3a2fa154b0fdd..856e02c9f1ddb 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3406,8 +3406,9 @@ Instruction *InstCombinerImpl::visitAllocSite(Instruction &MI) {
       // Replace invoke with a NOP intrinsic to maintain the original CFG
       Module *M = II->getModule();
       Function *F = Intrinsic::getOrInsertDeclaration(M, Intrinsic::donothing);
-      InvokeInst::Create(F, II->getNormalDest(), II->getUnwindDest(), {}, "",
-                         II->getParent());
+      auto *NewII = InvokeInst::Create(
+          F, II->getNormalDest(), II->getUnwindDest(), {}, "", II->getParent());
+      NewII->setDebugLoc(II->getDebugLoc());
     }
 
     // Remove debug intrinsics which describe the value contained within the
diff --git a/llvm/test/Transforms/InstCombine/debuginfo-invoke.ll b/llvm/test/Transforms/InstCombine/debuginfo-invoke.ll
new file mode 100644
index 0000000000000..287582b9baf3b
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/debuginfo-invoke.ll
@@ -0,0 +1,51 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=instcombine -S %s -o - | FileCheck %s
+
+define void @foo() personality ptr null !dbg !4 {
+; CHECK-LABEL: define void @foo(
+; CHECK-SAME: ) personality ptr null !dbg [[DBG3:![0-9]+]] {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    invoke void @llvm.donothing()
+; CHECK-NEXT:            to label %[[COMMON_RET:.*]] unwind label %[[LPAD159:.*]], !dbg [[DBG7:![0-9]+]]
+; CHECK:       [[COMMON_RET]]:
+; CHECK-NEXT:    ret void
+; CHECK:       [[LPAD159]]:
+; CHECK-NEXT:    [[TMP0:%.*]] = landingpad { ptr, i32 }
+; CHECK-NEXT:            cleanup
+; CHECK-NEXT:    br label %[[COMMON_RET]]
+;
+entry:
+  %call.i.i895904 = invoke ptr @_Znam(i64 0)
+          to label %common.ret unwind label %lpad159, !dbg !9
+
+common.ret:                                       ; preds = %lpad159, %entry
+  ret void
+
+lpad159:                                          ; preds = %entry
+  %0 = landingpad { ptr, i32 }
+  cleanup
+  br label %common.ret
+}
+
+declare ptr @_Znam(i64)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 20.0.0git")
+!1 = !DIFile(filename: "ArchiveCommandLine.cpp", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 13, type: !6, scopeLine: 13, unit: !0, retainedNodes: !2)
+!6 = distinct !DISubroutineType(types: !7)
+!7 = !{null}
+!9 = !DILocation(line: 14, column: 20, scope: !4)
+;.
+; CHECK: [[META0:![0-9]+]] = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: [[META1:![0-9]+]], producer: "{{.*}}clang version {{.*}}", isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
+; CHECK: [[META1]] = !DIFile(filename: "ArchiveCommandLine.cpp", directory: {{.*}})
+; CHECK: [[DBG3]] = distinct !DISubprogram(name: "foo", scope: [[META1]], file: [[META1]], line: 13, type: [[META4:![0-9]+]], scopeLine: 13, spFlags: DISPFlagDefinition, unit: [[META0]], retainedNodes: [[META6:![0-9]+]])
+; CHECK: [[META4]] = distinct !DISubroutineType(types: [[META5:![0-9]+]])
+; CHECK: [[META5]] = !{null}
+; CHECK: [[META6]] = !{}
+; CHECK: [[DBG7]] = !DILocation(line: 14, column: 20, scope: [[DBG3]])
+;.