[llvm] [indvars] Missing variables at Og: (PR #69920)

[Carlos Alberto Enciso via llvm-commits]

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@@ -0,0 +1,129 @@
+; RUN: opt -passes="loop(indvars)" \
+; RUN:     --experimental-debuginfo-iterators=false -S -o - < %s | \
+; RUN: FileCheck --implicit-check-not="call void @llvm.dbg" \
+; RUN:           --check-prefix=ALL-CHECK --check-prefix=PRE-CHECK %s
+; RUN: opt -passes="loop(indvars,loop-deletion)" \
+; RUN:     --experimental-debuginfo-iterators=false -S -o - < %s | \
+; RUN: FileCheck --implicit-check-not="call void @llvm.dbg" \
+; RUN:           --check-prefix=ALL-CHECK --check-prefix=POST-CHECK %s
+
+; Check what happens to a modified but otherwise unused variable in a loop
+; that gets deleted. The assignment in the loop is 'forgotten' by LLVM and
+; doesn't appear in the debugging information. This behaviour is suboptimal,
+; but we want to know if it changes
+
+; For all cases, LLDB shows
+;   Var = <no location, value may have been optimized out>
+
+;  1	__attribute__((optnone)) int nop() {
+;  2	  return 0;
+;  3	}
+;  4
+;  5	void bar() {
+;  6    int End = 777;
+;  7	  int Index = 27;
+;  8	  char Var = 1;
+;  9	  for (; Index < End; ++Index) {
+; 10      if (Index == 666) {
+; 11        ++Var;
+; 12      }
+; 13    }
+; 14	  nop();
+; 15	}
+
+; ALL-CHECK: entry:
+; ALL-CHECK:   call void @llvm.dbg.value(metadata i32 1, metadata ![[DBG:[0-9]+]], {{.*}}
+
+; Only the 'indvars' pass is executed.
+; PRE-CHECK: for.cond:
+; PRE-CHECK:   call void @llvm.dbg.value(metadata i32 %Var.0, metadata ![[DBG]], {{.*}}
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CarlosAlbertoEnciso wrote:

Thanks for the additional information. Changed to use `captured variables`.

https://github.com/llvm/llvm-project/pull/69920