Author: Stephen Tozer Date: 2025-01-28T18:25:32Z New Revision: 822f74a91106b7ca10e85508eb642e62ef945afa
URL: https://github.com/llvm/llvm-project/commit/822f74a91106b7ca10e85508eb642e62ef945afa DIFF: https://github.com/llvm/llvm-project/commit/822f74a91106b7ca10e85508eb642e62ef945afa.diff LOG: [Clang] Cleanup docs and comments relating to -fextend-variable-liveness (#124767) This patch contains a number of changes relating to the above flag; primarily it updates comment references to the old flag names, "-fextend-lifetimes" and "-fextend-this-ptr" to refer to the new names, "-fextend-variable-liveness[={all,this}]". These changes are all NFC. This patch also removes the explicit -fextend-this-ptr-liveness flag alias, and shortens the help-text for the main flag; these are both changes that were meant to be applied in the initial PR (#110000), but due to some user-error on my part they were not included in the merged commit. Added: Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Driver/Options.td clang/lib/CodeGen/CGDecl.cpp clang/lib/CodeGen/CodeGenFunction.h clang/test/CodeGen/fake-use-sanitizer.cpp clang/test/CodeGen/fake-use-this.cpp clang/test/Driver/extend-variable-liveness.c llvm/test/CodeGen/MIR/X86/fake-use-tailcall.mir llvm/test/CodeGen/X86/fake-use-simple-tail-call.ll llvm/test/CodeGen/X86/fake-use-zero-length.ll llvm/test/DebugInfo/AArch64/fake-use-global-isel.ll llvm/test/DebugInfo/X86/fake-use.ll llvm/test/Transforms/CodeGenPrepare/X86/fake-use-split-ret.ll llvm/test/Transforms/GVN/fake-use-constprop.ll Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index c5a5da5daf8f5e..74b09025967afc 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -524,15 +524,15 @@ New Compiler Flags Clang to generate code that tries to preserve the liveness of source variables through optimizations, meaning that variables will typically be visible in a debugger more often. The flag has two levels: ``-fextend-variable-liveness``, - or ``-fextend-variable-liveness=all``, extendes the liveness of all user - variables and the ``this`` pointer. Alternatively ``-fextend-this-ptr``, or - ``-fextend-variable-liveness=this``, has the same behaviour but applies only - to the ``this`` variable in C++ class member functions, meaning its effect is - a strict subset of ``-fextend-variable-liveness``. Note that this flag - modifies the results of optimizations that Clang performs, which will result - in reduced performance in generated code; however, this feature will not - extend the liveness of some variables in cases where doing so would likely - have a severe impact on generated code performance. + or ``-fextend-variable-liveness=all``, extends the liveness of all user + variables and the ``this`` pointer. Alternatively + ``-fextend-variable-liveness=this`` has the same behaviour but applies only to + the ``this`` variable in C++ class member functions, meaning its effect is a + strict subset of ``-fextend-variable-liveness``. Note that this flag modifies + the results of optimizations that Clang performs, which will result in reduced + performance in generated code; however, this feature will not extend the + liveness of some variables in cases where doing so would likely have a severe + impact on generated code performance. - The ``-Warray-compare`` warning has been added to warn about array comparison on versions older than C++20. diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td index 6fa8a8273aca34..2bf687895db294 100644 --- a/clang/include/clang/Driver/Options.td +++ b/clang/include/clang/Driver/Options.td @@ -4352,19 +4352,11 @@ def stack_usage_file : Separate<["-"], "stack-usage-file">, def fextend_variable_liveness_EQ : Joined<["-"], "fextend-variable-liveness=">, Group<f_Group>, Visibility<[ClangOption, CC1Option]>, HelpText<"Extend the liveness of user variables through optimizations to " - "prevent stale or optimized-out variable values when debugging. Can " - "be applied to all user variables, or just to the C++ 'this' ptr. " - "May choose not to extend the liveness of some variables, such as " - "non-scalars larger than 4 unsigned ints, or variables in any " - "inlined functions.">, + "prevent stale or optimized-out variable values when debugging." Values<"all,this,none">, NormalizedValues<["All", "This", "None"]>, NormalizedValuesScope<"CodeGenOptions::ExtendVariableLivenessKind">, MarshallingInfoEnum<CodeGenOpts<"ExtendVariableLiveness">, "None">; -def fextend_this_ptr_liveness : Flag<["-"], "fextend-this-ptr-liveness">, - Visibility<[ClangOption, CC1Option]>, - Alias<fextend_variable_liveness_EQ>, AliasArgs<["this"]>, - HelpText<"Alias for -fextend-variable-liveness=this.">; def fextend_variable_liveness : Flag<["-"], "fextend-variable-liveness">, Visibility<[ClangOption, CC1Option]>, Alias<fextend_variable_liveness_EQ>, AliasArgs<["all"]>, diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp index e0d2048262f8f1..747e420d031b6f 100644 --- a/clang/lib/CodeGen/CGDecl.cpp +++ b/clang/lib/CodeGen/CGDecl.cpp @@ -1423,7 +1423,7 @@ void CodeGenFunction::EmitAndRegisterVariableArrayDimensions( } /// Return the maximum size of an aggregate for which we generate a fake use -/// intrinsic when -fextend-lifetimes is in effect. +/// intrinsic when -fextend-variable-liveness is in effect. static uint64_t maxFakeUseAggregateSize(const ASTContext &C) { return 4 * C.getTypeSize(C.UnsignedIntTy); } diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h index 60f16a364d90d1..e978cad4336238 100644 --- a/clang/lib/CodeGen/CodeGenFunction.h +++ b/clang/lib/CodeGen/CodeGenFunction.h @@ -724,8 +724,8 @@ class CodeGenFunction : public CodeGenTypeCache { }; // We are using objects of this 'cleanup' class to emit fake.use calls - // for -fextend-lifetimes and -fextend-this-ptr. They are placed at the end of - // a variable's scope analogous to lifetime markers. + // for -fextend-variable-liveness. They are placed at the end of a variable's + // scope analogous to lifetime markers. class FakeUse final : public EHScopeStack::Cleanup { Address Addr; diff --git a/clang/test/CodeGen/fake-use-sanitizer.cpp b/clang/test/CodeGen/fake-use-sanitizer.cpp index d544bf85d2d9e4..e808c645b9c60f 100644 --- a/clang/test/CodeGen/fake-use-sanitizer.cpp +++ b/clang/test/CodeGen/fake-use-sanitizer.cpp @@ -1,7 +1,7 @@ // RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -emit-llvm -fextend-variable-liveness -fsanitize=null -fsanitize-trap=null -o - | FileCheck --check-prefixes=CHECK,NULL --implicit-check-not=ubsantrap %s // RUN: %clang_cc1 %s -triple x86_64-unknown-linux-gnu -emit-llvm -fextend-variable-liveness -o - | FileCheck %s -// With -fextend-lifetimes, the compiler previously generated a fake.use of any +// With -fextend-variable-liveness, the compiler previously generated a fake.use of any // reference variable at the end of the scope in which its alloca exists. This // caused two issues, where we would get fake uses for uninitialized variables // if that variable was declared after an early-return, and UBSan's null checks diff --git a/clang/test/CodeGen/fake-use-this.cpp b/clang/test/CodeGen/fake-use-this.cpp index 2c49694b2cd4fd..c1725d88c7176a 100644 --- a/clang/test/CodeGen/fake-use-this.cpp +++ b/clang/test/CodeGen/fake-use-this.cpp @@ -1,4 +1,4 @@ -// RUN: %clang_cc1 %s -emit-llvm -fextend-this-ptr-liveness -o - | FileCheck %s --implicit-check-not=fake.use +// RUN: %clang_cc1 %s -emit-llvm -fextend-variable-liveness=this -o - | FileCheck %s --implicit-check-not=fake.use // Check that we generate a fake_use call with the 'this' pointer as argument, // and no other fake uses. // The call should appear after the call to bar(). diff --git a/clang/test/Driver/extend-variable-liveness.c b/clang/test/Driver/extend-variable-liveness.c index bdd89d6f7721ce..bbfb2ece6f297e 100644 --- a/clang/test/Driver/extend-variable-liveness.c +++ b/clang/test/Driver/extend-variable-liveness.c @@ -4,7 +4,6 @@ // RUN: %clang -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,DEFAULT // RUN: %clang -fextend-variable-liveness=none -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,NONE // RUN: %clang -fextend-variable-liveness=this -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,THIS -// RUN: %clang -fextend-this-ptr-liveness -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,THIS // RUN: %clang -fextend-variable-liveness=all -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,ALL // RUN: %clang -fextend-variable-liveness -### -c %s 2>&1 | FileCheck %s --check-prefixes=CHECK,ALL diff --git a/llvm/test/CodeGen/MIR/X86/fake-use-tailcall.mir b/llvm/test/CodeGen/MIR/X86/fake-use-tailcall.mir index 6c2cb0e55222b2..3b833ae73551ab 100644 --- a/llvm/test/CodeGen/MIR/X86/fake-use-tailcall.mir +++ b/llvm/test/CodeGen/MIR/X86/fake-use-tailcall.mir @@ -8,7 +8,7 @@ # in the return block itself into the predecessor blocks. This test enures that we do so. # # Generated from the following source with -# clang -fextend-lifetimes -S -emit-llvm -O2 -mllvm -stop-before=codegenprepare -o test.mir test.c +# clang -fextend-variable-liveness -S -emit-llvm -O2 -mllvm -stop-before=codegenprepare -o test.mir test.c # # extern int f0(); # extern int f1(); diff --git a/llvm/test/CodeGen/X86/fake-use-simple-tail-call.ll b/llvm/test/CodeGen/X86/fake-use-simple-tail-call.ll index 45a210ef391009..fb01da9f12c8b4 100644 --- a/llvm/test/CodeGen/X86/fake-use-simple-tail-call.ll +++ b/llvm/test/CodeGen/X86/fake-use-simple-tail-call.ll @@ -1,6 +1,6 @@ ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -O2 -o - \ ; RUN: | FileCheck %s --implicit-check-not=TAILCALL -; Generated with: clang -emit-llvm -O2 -S -fextend-lifetimes test.cpp -o - +; Generated with: clang -emit-llvm -O2 -S -fextend-variable-liveness test.cpp -o - ; =========== test.cpp =============== ; extern int bar(int); ; int foo1(int i) diff --git a/llvm/test/CodeGen/X86/fake-use-zero-length.ll b/llvm/test/CodeGen/X86/fake-use-zero-length.ll index e3bdd2659dd913..71cb1029dcad65 100644 --- a/llvm/test/CodeGen/X86/fake-use-zero-length.ll +++ b/llvm/test/CodeGen/X86/fake-use-zero-length.ll @@ -4,7 +4,7 @@ ; and structs. Check also that they are not propagated. ; ; Generated from the following source with -; clang -fextend-lifetimes -S -emit-llvm -O2 -mllvm -stop-after=safe-stack -o test.mir test.cpp +; clang -fextend-variable-liveness -S -emit-llvm -O2 -mllvm -stop-after=safe-stack -o test.mir test.cpp ; ; int main () ; { int array[0]; } diff --git a/llvm/test/DebugInfo/AArch64/fake-use-global-isel.ll b/llvm/test/DebugInfo/AArch64/fake-use-global-isel.ll index 65a64583096959..2339b067c71e4f 100644 --- a/llvm/test/DebugInfo/AArch64/fake-use-global-isel.ll +++ b/llvm/test/DebugInfo/AArch64/fake-use-global-isel.ll @@ -12,7 +12,7 @@ ; RUN: not %python %p/../Inputs/check-fake-use.py %t ; Generated with: -; clang -O2 -g -S -emit-llvm -fextend-this-ptr fake-use.c +; clang -O2 -g -S -emit-llvm -fextend-variable-liveness=this fake-use.c ; ; int glob[10]; ; extern void bar(); diff --git a/llvm/test/DebugInfo/X86/fake-use.ll b/llvm/test/DebugInfo/X86/fake-use.ll index 5ac5104a167118..0f24ab40ba9ad0 100644 --- a/llvm/test/DebugInfo/X86/fake-use.ll +++ b/llvm/test/DebugInfo/X86/fake-use.ll @@ -9,7 +9,7 @@ ; RUN: not %python %p/../Inputs/check-fake-use.py %t ; Generated with: -; clang -O2 -g -S -emit-llvm -fextend-this-ptr fake-use.c +; clang -O2 -g -S -emit-llvm -fextend-variable-liveness=this fake-use.c ; ; int glob[10]; ; extern void bar(); diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/fake-use-split-ret.ll b/llvm/test/Transforms/CodeGenPrepare/X86/fake-use-split-ret.ll index b2cf89f6f2dd82..9f356b5e3cb427 100644 --- a/llvm/test/Transforms/CodeGenPrepare/X86/fake-use-split-ret.ll +++ b/llvm/test/Transforms/CodeGenPrepare/X86/fake-use-split-ret.ll @@ -2,7 +2,7 @@ ; ; Ensure return instruction splitting ignores fake uses. ; -; IR Generated with clang -O2 -S -emit-llvm -fextend-lifetimes test.cpp +; IR Generated with clang -O2 -S -emit-llvm -fextend-variable-liveness test.cpp ; ;// test.cpp ;extern int bar(int); diff --git a/llvm/test/Transforms/GVN/fake-use-constprop.ll b/llvm/test/Transforms/GVN/fake-use-constprop.ll index 1466f9f9fca277..0e7ca101a2524a 100644 --- a/llvm/test/Transforms/GVN/fake-use-constprop.ll +++ b/llvm/test/Transforms/GVN/fake-use-constprop.ll @@ -7,7 +7,7 @@ ; with respect to keeping the variable live up until the fake.use. ; This test checks that we don't generate any fake.uses with constant 0. ; -; Reduced from the following test case, generated with clang -O2 -S -emit-llvm -fextend-lifetimes test.c +; Reduced from the following test case, generated with clang -O2 -S -emit-llvm -fextend-variable-liveness test.c ; ; extern void func1(); ; extern int bar(); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
