[llvm] [DebugInfo][RemoveDIs] Add flag to use "new" debug-info in opt (PR #71937)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse updated https://github.com/llvm/llvm-project/pull/71937

>From 9e5cf9c2c9ec498d87803f5f732a2d5417a0dbca Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Fri, 10 Nov 2023 10:22:34 +0000
Subject: [PATCH 1/4] [DebugInfo][RemoveDIs] Add flag to use "new" debug-info 
 in opt

The option to turn on the non-intrinsic form of debug-info currently
requires that LLVM is built with the LLVM_EXPERIMENTAL_DEBUGINFO_ITERATORS
cmake flag enabled, so that some (slight) performance regressions aren't
on-by-default during the prototype/testing period. However, we still want
to be able to _optionally_ run tests, if support is built into LLVM.

Hence adding this flag, --try-experimental-debuginfo-iterators. This turns
the --experimental-debuginfo-iterators flag on if support is built in, or
leaves it off. This means we can run tests that:
 * Use normal dbg.value intrinsics if there's no support, or
 * Uses non-instruction DPValues if there is support.
Which means we can start getting test coverage of DPValues/RemoveDIs
behaviour, from in-tree tests, on our RemoveDIs buildbot.
---
 llvm/tools/opt/opt.cpp | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index bb6627364442ef7..129f754eedda71d 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -279,6 +279,12 @@ static cl::list<std::string>
     PassPlugins("load-pass-plugin",
                 cl::desc("Load passes from plugin library"));
 
+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;
+
 //===----------------------------------------------------------------------===//
 // CodeGen-related helper functions.
 //
@@ -438,6 +444,19 @@ int main(int argc, char **argv) {
   initializeReplaceWithVeclibLegacyPass(Registry);
   initializeJMCInstrumenterPass(Registry);
 
+  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
+  // new debug-info format, if it's built in.
+  if (TryUseNewDbgInfoFormat) {
+#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+    // If LLVM was built with support for this, turn the new debug-info format
+    // on.
+    UseNewDbgInfoFormat = true;
+#else
+    // It it wasn't, do nothing.
+    ;
+#endif
+  }
+
   SmallVector<PassPlugin, 1> PluginList;
   PassPlugins.setCallback([&](const std::string &PluginPath) {
     auto Plugin = PassPlugin::Load(PluginPath);

>From 93b94f59a61f109d2182e5665c5aaba3b50e37ef Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Mon, 13 Nov 2023 14:26:55 +0000
Subject: [PATCH 2/4] Check flags after we've parsed the command line

---
 llvm/tools/opt/opt.cpp | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 129f754eedda71d..080ce4235ce79ab 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -444,19 +444,6 @@ int main(int argc, char **argv) {
   initializeReplaceWithVeclibLegacyPass(Registry);
   initializeJMCInstrumenterPass(Registry);
 
-  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
-  // new debug-info format, if it's built in.
-  if (TryUseNewDbgInfoFormat) {
-#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
-    // If LLVM was built with support for this, turn the new debug-info format
-    // on.
-    UseNewDbgInfoFormat = true;
-#else
-    // It it wasn't, do nothing.
-    ;
-#endif
-  }
-
   SmallVector<PassPlugin, 1> PluginList;
   PassPlugins.setCallback([&](const std::string &PluginPath) {
     auto Plugin = PassPlugin::Load(PluginPath);
@@ -471,6 +458,19 @@ int main(int argc, char **argv) {
   cl::ParseCommandLineOptions(argc, argv,
     "llvm .bc -> .bc modular optimizer and analysis printer\n");
 
+  // RemoveDIs debug-info transition: tests may request that we /try/ to use the
+  // new debug-info format, if it's built in.
+  if (TryUseNewDbgInfoFormat) {
+#ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+    // If LLVM was built with support for this, turn the new debug-info format
+    // on.
+    UseNewDbgInfoFormat = true;
+#else
+    // It it wasn't, do nothing.
+    ;
+#endif
+  }
+
   LLVMContext Context;
 
   // TODO: remove shouldForceLegacyPM().

>From d426d293f361b002f09696f83c979fe3ffb91975 Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Mon, 13 Nov 2023 14:33:24 +0000
Subject: [PATCH 3/4] Simplify away some un-necessary lines

---
 llvm/tools/opt/opt.cpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 080ce4235ce79ab..81b3e1f240397e9 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -460,16 +460,14 @@ int main(int argc, char **argv) {
 
   // RemoveDIs debug-info transition: tests may request that we /try/ to use the
   // new debug-info format, if it's built in.
-  if (TryUseNewDbgInfoFormat) {
 #ifdef EXPERIMENTAL_DEBUGINFO_ITERATORS
+  if (TryUseNewDbgInfoFormat) {
     // If LLVM was built with support for this, turn the new debug-info format
     // on.
     UseNewDbgInfoFormat = true;
-#else
-    // It it wasn't, do nothing.
-    ;
-#endif
   }
+#endif
+  (void)TryUseNewDbgInfoFormat;
 
   LLVMContext Context;
 

>From 4f8c8eaabbffa0fc68ae9f4cfdc0d2b4fc985c2a Mon Sep 17 00:00:00 2001
From: Jeremy Morse <jeremy.morse at sony.com>
Date: Mon, 13 Nov 2023 14:34:17 +0000
Subject: [PATCH 4/4] Clang-format

---
 llvm/tools/opt/opt.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/tools/opt/opt.cpp b/llvm/tools/opt/opt.cpp
index 81b3e1f240397e9..5e5e5ce233f310a 100644
--- a/llvm/tools/opt/opt.cpp
+++ b/llvm/tools/opt/opt.cpp
@@ -279,7 +279,8 @@ static cl::list<std::string>
     PassPlugins("load-pass-plugin",
                 cl::desc("Load passes from plugin library"));
 
-static cl::opt<bool> TryUseNewDbgInfoFormat("try-experimental-debuginfo-iterators",
+static cl::opt<bool> TryUseNewDbgInfoFormat(
+    "try-experimental-debuginfo-iterators",
     cl::desc("Enable debuginfo iterator positions, if they're built in"),
     cl::init(false));