[llvm] [DebugInfo][InstCombine] Propagate DILocation when noop-ing invoke (PR #134678)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer created https://github.com/llvm/llvm-project/pull/134678

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 https://github.com/llvm/llvm-project/pull/107279.

>From 779bda4a47c79452ce127fff7cb0b659fe70fc75 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <stephen.tozer at sony.com>
Date: Tue, 29 Oct 2024 20:03:28 +0000
Subject: [PATCH] [DebugInfo][InstCombine] When replacing invoke with nop,
 propagate DILocation

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.
---
 .../InstCombine/InstructionCombining.cpp      |  5 +-
 .../InstCombine/debuginfo-invoke.ll           | 51 +++++++++++++++++++
 2 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/Transforms/InstCombine/debuginfo-invoke.ll

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]])
+;.