[RemoveDIs] Preserve debug info format in llvm-reduce (#89220)

As the goal of LLVM reduce is to simplify the input file, it should not
modify the debug info format - doing so by default would make it
impossible to reduce an error that only occurs in the old format, for
example (as briefly discussed at
#86275). This patch uses the
new "preserve debug info format" flag in llvm-reduce to prevent the
input from being subtly transformed by llvm-reduce itself; this has no
effect on any tools used for the interestingness check (i.e. if `opt` is
invoked, it will still convert the reduced input to the new format by
default), but simply ensures that the reduced file is strictly reduced
rather than modified.

Author: SLTozer

llvm/test/tools/llvm-reduce/remove-dp-values.ll

@@ -1,17 +1,21 @@
-; RUN: llvm-reduce --abort-on-invalid-reduction --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t --try-experimental-debuginfo-iterators
-; RUN: FileCheck --check-prefixes=CHECK-FINAL --input-file=%t %s --implicit-check-not=dbg.value
+; RUN: llvm-reduce --abort-on-invalid-reduction --test FileCheck --test-arg --check-prefixes=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck --check-prefixes=CHECK-FINAL --input-file=%t %s --implicit-check-not=#dbg_value
+
+; RUN: opt < %s -S --write-experimental-debuginfo=false > %t.intrinsics.ll
+; RUN: llvm-reduce --abort-on-invalid-reduction --test FileCheck --test-arg --check-prefixes=INTRINSIC-INTERESTINGNESS --test-arg %s --test-arg --input-file %t.intrinsics.ll -o %t
+; RUN: FileCheck --check-prefixes=INTRINSIC-FINAL --input-file=%t %s --implicit-check-not=#dbg_value
 
 ; Test that we can, in RemoveDIs mode / DbgVariableRecords mode (where variable location
 ; information isn't an instruction), remove one variable location assignment
 ; but not another.
 
-; CHECK-INTERESTINGNESS:     call void @llvm.dbg.value(metadata i32 %added,
-
-; CHECK-FINAL:     declare void @llvm.dbg.value(metadata,
-; CHECK-FINAL:     %added = add
-; CHECK-FINAL-NEXT: call void @llvm.dbg.value(metadata i32 %added,
+; CHECK-INTERESTINGNESS:     #dbg_value(i32 %added,
+; INTRINSIC-INTERESTINGNESS: llvm.dbg.value(metadata i32 %added,
 
-declare void @llvm.dbg.value(metadata, metadata, metadata)
+; CHECK-FINAL:      %added = add
+; CHECK-FINAL-NEXT: #dbg_value(i32 %added,
+; INTRINSIC-FINAL:      %added = add
+; INTRINSIC-FINAL-NEXT: llvm.dbg.value(metadata i32 %added,
 
 define i32 @main() !dbg !7 {
 entry:
@@ -22,10 +26,10 @@ entry:
   store i32 0, ptr %interesting, align 4
   %0 = load i32, ptr %interesting, align 4
   %added = add nsw i32 %0, 1
-  tail call void @llvm.dbg.value(metadata i32 %added, metadata !13, metadata !DIExpression()), !dbg !14
+    #dbg_value(i32 %added, !13, !DIExpression(), !14)
   store i32 %added, ptr %interesting, align 4
   %alsoloaded = load i32, ptr %interesting, align 4
-  tail call void @llvm.dbg.value(metadata i32 %alsoloaded, metadata !13, metadata !DIExpression()), !dbg !14
+    #dbg_value(i32 %alsoloaded, !13, !DIExpression(), !14)
   store i32 %alsoloaded, ptr %uninteresting2, align 4
   ret i32 0
 }

llvm/tools/llvm-reduce/llvm-reduce.cpp

@@ -100,12 +100,7 @@ static cl::opt<int>
                                "of delta passes (default=5)"),
                       cl::init(5), cl::cat(LLVMReduceOptions));
 
-static cl::opt<bool> TryUseNewDbgInfoFormat(
-    "try-experimental-debuginfo-iterators",
-    cl::desc("Enable debuginfo iterator positions, if they're built in"),
-    cl::init(false));
-
-extern cl::opt<bool> UseNewDbgInfoFormat;
+extern cl::opt<cl::boolOrDefault> PreserveInputDbgFormat;
 
 static codegen::RegisterCodeGenFlags CGF;
 
@@ -146,17 +141,11 @@ static std::pair<StringRef, bool> determineOutputType(bool IsMIR,
 int main(int Argc, char **Argv) {
   InitLLVM X(Argc, Argv);
   const StringRef ToolName(Argv[0]);
+  PreserveInputDbgFormat = cl::boolOrDefault::BOU_TRUE;
 
   cl::HideUnrelatedOptions({&LLVMReduceOptions, &getColorCategory()});
   cl::ParseCommandLineOptions(Argc, Argv, "LLVM automatic testcase reducer.\n");
 
-  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
-  // new debug-info format.
-  if (TryUseNewDbgInfoFormat) {
-    // Turn the new debug-info format on.
-    UseNewDbgInfoFormat = true;
-  }
-
   if (Argc == 1) {
     cl::PrintHelpMessage();
     return 0;