https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/229674
For IR input, CodeGenAction forces setDiscardValueNames(false) to avoid the crash in #44241, so names created by the optimizer (e.g. the inliner's `.i`) are kept. c53d807321f6 fixed that crash in Value::setNameImpl. Apply CodeGenOpts.DiscardValueNames after loading the module and remove the "ignoring -fdiscard-value-names" warning. LLM-aided. `clang -O3 -c sqlite3.bc` executes 0.7% fewer instructions. >From 98adde678eb3d952fbbe2dddcd11a4d596838ff5 Mon Sep 17 00:00:00 2001 From: Fangrui Song <[email protected]> Date: Tue, 6 Oct 2026 22:46:52 -0700 Subject: [PATCH] [clang] Honor -discard-value-names for LLVM IR input For IR input, CodeGenAction forces setDiscardValueNames(false) to avoid the crash in #44241, so names created by the optimizer (e.g. the inliner's `.i`) are kept. c53d807321f6 fixed that crash in Value::setNameImpl. Apply CodeGenOpts.DiscardValueNames after loading the module and remove the "ignoring -fdiscard-value-names" warning. LLM-aided. `clang -O3 -c sqlite3.bc` executes 0.7% fewer instructions. --- .../clang/Basic/DiagnosticDriverKinds.td | 3 --- clang/lib/CodeGen/CodeGenAction.cpp | 5 ++--- clang/lib/Driver/ToolChains/Clang.cpp | 9 +------- clang/test/CodeGen/PR44896.ll | 16 -------------- clang/test/CodeGen/discard-name-values.ll | 21 +++++++++++++++++++ 5 files changed, 24 insertions(+), 30 deletions(-) delete mode 100644 clang/test/CodeGen/PR44896.ll create mode 100644 clang/test/CodeGen/discard-name-values.ll diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td index df6ff0c2cf399f6..e8a66dae748fff6 100644 --- a/clang/include/clang/Basic/DiagnosticDriverKinds.td +++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td @@ -487,9 +487,6 @@ def warn_drv_dwarf_version_limited_by_target : Warning< InGroup<UnsupportedTargetOpt>; def warn_c_kext : Warning< "ignoring -fapple-kext which is valid for C++ and Objective-C++ only">; -def warn_ignoring_fdiscard_for_bitcode : Warning< - "ignoring -fdiscard-value-names for LLVM Bitcode">, - InGroup<UnusedCommandLineArgument>; def warn_drv_input_file_unused : Warning< "%0: '%1' input unused%select{ when '%3' is present|}2">, InGroup<UnusedCommandLineArgument>; diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp index de677a385d832be..1abd8b0455a19b3 100644 --- a/clang/lib/CodeGen/CodeGenAction.cpp +++ b/clang/lib/CodeGen/CodeGenAction.cpp @@ -617,9 +617,8 @@ void CodeGenAction::ExecuteAction() { if (!CodeGenOpts.LinkBitcodePostopt && Result.LinkInModules(&*TheModule)) return; - // PR44896: Force DiscardValueNames as false. DiscardValueNames cannot be - // true here because the valued names are needed for reading textual IR. - Ctx.setDiscardValueNames(false); + // Textual IR needs value names while parsing; discard new names afterwards. + Ctx.setDiscardValueNames(CodeGenOpts.DiscardValueNames); Ctx.setDiagnosticHandler(Result.createDiagnosticHandler()); Ctx.setDefaultTargetCPU(TargetOpts.CPU); diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp index 33507396561e215..2325e7cc552ef9f 100644 --- a/clang/lib/Driver/ToolChains/Clang.cpp +++ b/clang/lib/Driver/ToolChains/Clang.cpp @@ -5797,15 +5797,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, // Discard value names in no-asserts builds unless otherwise specified. if (Args.hasFlag(options::OPT_fdiscard_value_names, - options::OPT_fno_discard_value_names, !IsAssertBuild)) { - if (Args.hasArg(options::OPT_fdiscard_value_names) && - llvm::any_of(Inputs, [](const clang::driver::InputInfo &II) { - return types::isLLVMIR(II.getType()); - })) { - D.Diag(diag::warn_ignoring_fdiscard_for_bitcode); - } + options::OPT_fno_discard_value_names, !IsAssertBuild)) CmdArgs.push_back("-discard-value-names"); - } // Set the main file name, so that debug info works even with // -save-temps. diff --git a/clang/test/CodeGen/PR44896.ll b/clang/test/CodeGen/PR44896.ll deleted file mode 100644 index 6547ea12168f65d..000000000000000 --- a/clang/test/CodeGen/PR44896.ll +++ /dev/null @@ -1,16 +0,0 @@ -; REQUIRES: x86-registered-target -; RUN: %clang --target=x86_64-linux-gnu -fdiscard-value-names -S %s -o /dev/null 2>&1 | FileCheck --check-prefix=WARNING %s -; RUN: %clang --target=x86_64-linux-gnu -S %s -o /dev/null 2>&1 | FileCheck --check-prefix=NOWARNING %s -; RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm %s -discard-value-names -o /dev/null -; PR 44896 - -; WARNING: ignoring -fdiscard-value-names for LLVM Bitcode -; NOWARNING-NOT: ignoring -fdiscard-value-names for LLVM Bitcode - -target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128" -target triple = "x86_64--linux-gnu" - -define linkonce ptr @b(ptr %a) { - ret ptr %a -} - diff --git a/clang/test/CodeGen/discard-name-values.ll b/clang/test/CodeGen/discard-name-values.ll new file mode 100644 index 000000000000000..246bca2d102a594 --- /dev/null +++ b/clang/test/CodeGen/discard-name-values.ll @@ -0,0 +1,21 @@ +; REQUIRES: x86-registered-target +;; Textual IR keeps its names while parsing; -discard-value-names only drops +;; names created afterwards (here by the inliner). +; RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O1 -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,KEEP +; RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O1 -emit-llvm %s -discard-value-names -o - | FileCheck %s --check-prefixes=CHECK,DISCARD + +; CHECK-LABEL: define {{.*}} @g(i32 {{.*}}%a) +; KEEP: %y.i = add i32 %a, 1 +; DISCARD: %1 = add i32 %a, 1 + +target triple = "x86_64-unknown-linux-gnu" + +define internal i32 @f(i32 %x) { + %y = add i32 %x, 1 + ret i32 %y +} + +define i32 @g(i32 %a) { + %r = call i32 @f(i32 %a) + ret i32 %r +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
