[clang] [Clang][Driver] Add new flags to control IR verification (PR #68172)

[Arthur Eubanks via cfe-commits]

https://github.com/aeubanks updated https://github.com/llvm/llvm-project/pull/68172

>From a5414db5e14cb40d062e54e780293cabc432197a Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov at gmail.com>
Date: Wed, 4 Oct 2023 04:39:11 +0200
Subject: [PATCH 1/2] [Clang][Driver] Add new flags to control IR verification

---
 clang/docs/ReleaseNotes.rst           | 7 +++++++
 clang/include/clang/Driver/Options.td | 6 ++++++
 clang/lib/Driver/ToolChains/Clang.cpp | 6 ++++--
 clang/test/Driver/clang_f_opts.c      | 5 +++++
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 6f410c48bd1ffe9..62f939b54d3dd14 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -146,6 +146,13 @@ Non-comprehensive list of changes in this release
 
 New Compiler Flags
 ------------------
+* ``-fverify-intermediate-code`` and it's complement ``-fno-verify-intermediate-code``.
+  Enables or disables verification of the generated LLVM IR.
+  Users can pass this to turn on extra verification to catch certain types of
+  compiler bugs at the cost of extra compile time.
+  Since enabling the verifier adds a non-trivial cost of a few percent impact on
+  build times, it's disabled by default, unless your LLVM distribution itself is
+  compiled with runtime checks enabled.
 
 Deprecated Compiler Flags
 -------------------------
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 7f7024b4ddb50c1..08dd7c6d1bb67ff 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1909,6 +1909,12 @@ defm safe_buffer_usage_suggestions : BoolFOption<"safe-buffer-usage-suggestions"
   PosFlag<SetTrue, [], [ClangOption, CC1Option],
           "Display suggestions to update code associated with -Wunsafe-buffer-usage warnings">,
   NegFlag<SetFalse>>;
+def fverify_intermediate_code : Flag<["-"], "fverify-intermediate-code">,
+  Group<f_clang_Group>, Visibility<[ClangOption, CLOption, DXCOption]>,
+  HelpText<"Enable verification of LLVM IR">, Flags<[NoXarchOption]>;
+def fno_verify_intermediate_code : Flag<["-"], "fno-verify-intermediate-code">,
+  Group<f_clang_Group>, Visibility<[ClangOption, CLOption, DXCOption]>,
+  HelpText<"Disable verification of LLVM IR">, Flags<[NoXarchOption]>;
 def fdiscard_value_names : Flag<["-"], "fdiscard-value-names">,
   Group<f_clang_Group>, Visibility<[ClangOption, DXCOption]>,
   HelpText<"Discard value names in LLVM IR">, Flags<[NoXarchOption]>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index fc3615245000109..c74f6ff447261dc 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5150,9 +5150,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   const bool IsAssertBuild = true;
 #endif
 
-  // Disable the verification pass in -asserts builds.
-  if (!IsAssertBuild)
+  // Disable the verification pass in asserts builds unless otherwise specified.
+  if (Args.hasFlag(options::OPT_fno_verify_intermediate_code,
+                   options::OPT_fverify_intermediate_code, !IsAssertBuild)) {
     CmdArgs.push_back("-disable-llvm-verifier");
+  }
 
   // Discard value names in assert builds unless otherwise specified.
   if (Args.hasFlag(options::OPT_fdiscard_value_names,
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index 7a3616a2e9f0a48..ebe8a0520bf0fca 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -520,6 +520,11 @@
 // CHECK-COVERAGE-COMPILATION-DIR: "-fcoverage-compilation-dir=."
 // CHECK-COVERAGE-COMPILATION-DIR-NOT: "-ffile-compilation-dir=."
 
+// RUN: %clang -### -S -fverify-intermediate-code %s 2>&1 | FileCheck -check-prefix=CHECK-VERIFY-INTERMEDIATE-CODE %s
+// RUN: %clang -### -S -fno-verify-intermediate-code %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VERIFY-INTERMEDIATE-CODE %s
+// CHECK-VERIFY-INTERMEDIATE-CODE-NOT: "-disable-llvm-verifier"
+// CHECK-NO-VERIFY-INTERMEDIATE-CODE: "-disable-llvm-verifier"
+
 // RUN: %clang -### -S -fdiscard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-DISCARD-NAMES %s
 // RUN: %clang -### -S -fno-discard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-NO-DISCARD-NAMES %s
 // CHECK-DISCARD-NAMES: "-discard-value-names"

>From 6fa96a393b286f8725c5ae1784796e9ba8e68f68 Mon Sep 17 00:00:00 2001
From: Arthur Eubanks <ayueubanks at gmail.com>
Date: Wed, 4 Oct 2023 12:57:49 -0700
Subject: [PATCH 2/2] Update ReleaseNotes.rst

---
 clang/docs/ReleaseNotes.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 62f939b54d3dd14..23cc8cfe3b2773c 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -146,7 +146,7 @@ Non-comprehensive list of changes in this release
 
 New Compiler Flags
 ------------------
-* ``-fverify-intermediate-code`` and it's complement ``-fno-verify-intermediate-code``.
+* ``-fverify-intermediate-code`` and its complement ``-fno-verify-intermediate-code``.
   Enables or disables verification of the generated LLVM IR.
   Users can pass this to turn on extra verification to catch certain types of
   compiler bugs at the cost of extra compile time.