Author: Arthur Eubanks Date: 2021-10-06T13:42:22-07:00 New Revision: 6522b7cc3240626952ebc271d8714043a805911d
URL: https://github.com/llvm/llvm-project/commit/6522b7cc3240626952ebc271d8714043a805911d DIFF: https://github.com/llvm/llvm-project/commit/6522b7cc3240626952ebc271d8714043a805911d.diff LOG: [clang] Add option to clear AST memory before running LLVM passes This is to save memory for Clang compiles. Measuring building PassBuilder.cpp under /usr/bin/time, max rss goes from 0.93GB to 0.7GB. This does not turn it by default yet. I've turned on the option locally and run it over a good amount of files without any issues. For more background, see https://lists.llvm.org/pipermail/cfe-dev/2021-September/068930.html. Reviewed By: dblaikie Differential Revision: https://reviews.llvm.org/D111105 Added: clang/test/Misc/clear-ast-before-backend.c Modified: clang/include/clang/Basic/CodeGenOptions.def clang/include/clang/Driver/Options.td clang/lib/CodeGen/CodeGenAction.cpp Removed: ################################################################################ diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def index df4f8db6e16c..610123260175 100644 --- a/clang/include/clang/Basic/CodeGenOptions.def +++ b/clang/include/clang/Basic/CodeGenOptions.def @@ -54,6 +54,7 @@ CODEGENOPT(UniqueBasicBlockSectionNames, 1, 1) ///< Set for -funique-basic-block CODEGENOPT(EnableAIXExtendedAltivecABI, 1, 0) ///< Set for -mabi=vec-extabi. Enables the extended Altivec ABI on AIX. ENUM_CODEGENOPT(FramePointer, FramePointerKind, 2, FramePointerKind::None) /// frame-pointer: all,non-leaf,none +CODEGENOPT(ClearASTBeforeBackend , 1, 0) ///< Free the AST before running backend code generation. Only works with -disable-free. CODEGENOPT(DisableFree , 1, 0) ///< Don't free memory. CODEGENOPT(DiscardValueNames , 1, 0) ///< Discard Value Names from the IR (LLVMContext flag) CODEGENOPT(DisableLLVMPasses , 1, 0) ///< Don't run any LLVM IR passes to get diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index f2c119ad3794..7d1e6d181f97 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -5297,6 +5297,9 @@ def code_completion_with_fixits : Flag<["-"], "code-completion-with-fixits">, def disable_free : Flag<["-"], "disable-free">, HelpText<"Disable freeing of memory on exit">, MarshallingInfoFlag<FrontendOpts<"DisableFree">>; +def clear_ast_before_backend : Flag<["-"], "clear-ast-before-backend">, + HelpText<"Clear the Clang AST before running backend code generation">, + MarshallingInfoFlag<CodeGenOpts<"ClearASTBeforeBackend">>; def enable_noundef_analysis : Flag<["-"], "enable-noundef-analysis">, Group<f_Group>, HelpText<"Enable analyzing function argument and return types for mandatory definedness">, MarshallingInfoFlag<CodeGenOpts<"EnableNoundefAttrs">>; diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp index 9fb5f29c94ab..4ca34db06ced 100644 --- a/clang/lib/CodeGen/CodeGenAction.cpp +++ b/clang/lib/CodeGen/CodeGenAction.cpp @@ -351,6 +351,11 @@ namespace clang { } } + // FIXME: Fix cleanup issues with clearing the AST when we properly free + // things. + if (CodeGenOpts.DisableFree && CodeGenOpts.ClearASTBeforeBackend) + C.getAllocator().Reset(); + EmbedBitcode(getModule(), CodeGenOpts, llvm::MemoryBufferRef()); EmitBackendOutput(Diags, HeaderSearchOpts, CodeGenOpts, TargetOpts, diff --git a/clang/test/Misc/clear-ast-before-backend.c b/clang/test/Misc/clear-ast-before-backend.c new file mode 100644 index 000000000000..8e46d3bcb068 --- /dev/null +++ b/clang/test/Misc/clear-ast-before-backend.c @@ -0,0 +1,3 @@ +// RUN: %clang_cc1 -clear-ast-before-backend %s -emit-obj -o /dev/null -O1 + +void f() {} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
