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[Clang][Driver] Add new flags to control IR verification #68172

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Merged
merged 2 commits into from
Oct 4, 2023
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[Clang][Driver] Add new flags to control IR verification #68172

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a5414db
[Clang][Driver] Add new flags to control IR verification
mizvekov Oct 4, 2023
6fa96a3
Update ReleaseNotes.rst
aeubanks Oct 4, 2023
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7 changes: 7 additions & 0 deletions clang/docs/ReleaseNotes.rst
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Expand Up @@ -146,6 +146,13 @@ Non-comprehensive list of changes in this release

New Compiler Flags
------------------
* ``-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.
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
-------------------------
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6 changes: 6 additions & 0 deletions clang/include/clang/Driver/Options.td
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Expand Up @@ -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]>;
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6 changes: 4 additions & 2 deletions clang/lib/Driver/ToolChains/Clang.cpp
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Expand Up @@ -5150,9 +5150,11 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
const bool IsAssertBuild = true;
#endif

// Disable the verification pass in -asserts builds.
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Hmm, I might be missing something here, but doesn't this disable the verifier for builds without assertions?

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I edited the line to append the unless otherwise specified, since now we allow overriding that with the new flag.

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,
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5 changes: 5 additions & 0 deletions clang/test/Driver/clang_f_opts.c
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Expand Up @@ -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"
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