[clang] [DebugInfo] Correct the line attribution for IF branches (PR #108300)

[Paul T Robinson via cfe-commits]

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@@ -0,0 +1,45 @@
+// RUN: %clang_cc1 -debug-info-kind=limited -gno-column-info -triple=x86_64-pc-linux -emit-llvm %s -o - | FileCheck  %s
+
+// The important thing is that the compare and the conditional branch have
+// locs with the same scope (the lexical block for the 'if'). By turning off
+// column info, they end up with the same !dbg record, which halves the number
+// of checks to verify the scope.
+
+int c = 2;
+
+int f() {
+#line 100
+  if (int a = 5; a > c)
+    return 1;
+  return 0;
+}
+// CHECK-LABEL: define {{.*}} @_Z1fv()
+// CHECK:       = icmp {{.*}} !dbg [[F_CMP:![0-9]+]]
+// CHECK-NEXT:  br i1 {{.*}} !dbg [[F_CMP]]
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pogo59 wrote:

Re. other statements: `while` does not appear to have a problem, however `for` does. Looking at the implementation, I would have expected it to crop up only when the first `for` clause is empty, but in fact it happens regardless. It conjures up not one but two DILexicalBlocks, both pointing to the `for` keyword. I'd prefer to look into that more deeply as a separate task.

https://github.com/llvm/llvm-project/pull/108300