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[Driver] -pg -mfentry should respect target specific decisions for -mframe-pointer=all

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Summary:
$ clang -O2 -pg -mfentry foo.c

was adding frame pointers to all functions. This was exposed via
compiling the Linux kernel for x86_64 with CONFIG_FUNCTION_TRACER
enabled.

-pg was unconditionally setting the equivalent of -fno-omit-frame-pointer,
regardless of the presence of -mfentry or optimization level.  After this
patch, frame pointers will only be omitted at -O0 or if
-fno-omit-frame-pointer is explicitly set for -pg -mfentry.

See also:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=3c5273a96ba8dbf98c40bc6d9d0a1587b4cfedb2;hp=c9d75a48c4ea63ab27ccdb40f993236289b243f2#patch2
(modification to ix86_frame_pointer_required())

Fixes: pr/44934

Reviewers: void, manojgupta, dberris, MaskRay, hfinkel

Reviewed By: MaskRay

Subscribers: cfe-commits, llozano, niravd, srhines

Tags: #clang

Differential Revision: https://reviews.llvm.org/D74698
This commit is contained in:
Nick Desaulniers
2020-02-18 15:33:42 -08:00
parent 1f44134243
commit 8b9cb12081
2 changed files with 13 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
clang/lib/Driver/ToolChains/Clang.cpp
View File

@@ -526,7 +526,7 @@ static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) {
static bool useFramePointerForTargetByDefault(const ArgList &Args,
const llvm::Triple &Triple) {
if (Args.hasArg(options::OPT_pg))
if (Args.hasArg(options::OPT_pg) && !Args.hasArg(options::OPT_mfentry))
return true;
switch (Triple.getArch()) {
@@ -6150,7 +6150,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
}
if (Arg *A = Args.getLastArg(options::OPT_pg))
if (FPKeepKind == CodeGenOptions::FramePointerKind::None)
if (FPKeepKind == CodeGenOptions::FramePointerKind::None &&
!Args.hasArg(options::OPT_mfentry))
D.Diag(diag::err_drv_argument_not_allowed_with) << "-fomit-frame-pointer"
<< A->getAsString(Args);

10
clang/test/Driver/mfentry.c
View File

@@ -1,9 +1,19 @@
// RUN: %clang -target s390x -c -### %s -mfentry 2>&1 | FileCheck %s
// RUN: %clang -target i386 -c -### %s -mfentry 2>&1 | FileCheck %s
// RUN: %clang -target x86_64 -c -### %s -mfentry 2>&1 | FileCheck %s
// RUN: %clang -target x86_64-linux-gnu -pg -mfentry -O0 -### -E %s 2>&1 | FileCheck -check-prefix=FP %s
// RUN: %clang -target x86_64-linux-gnu -pg -mfentry -O2 -fno-omit-frame-pointer -### -E %s 2>&1 | FileCheck -check-prefix=FP %s
// RUN: %clang -target x86_64-linux-gnu -pg -mfentry -O2 -### -E %s 2>&1 | FileCheck -check-prefix=NOFP %s
// RUN: %clang -target x86_64 -pg -mfentry -O0 -### -E %s 2>&1 | FileCheck -check-prefix=FP %s
// RUN: %clang -target x86_64 -pg -mfentry -O2 -fno-omit-frame-pointer -### -E %s 2>&1 | FileCheck -check-prefix=FP %s
// RUN: %clang -target x86_64 -pg -mfentry -O2 -### -E %s 2>&1 | FileCheck -check-prefix=FP %s
// CHECK: "-mfentry"
// RUN: %clang -target powerpc64le -c -### %s -mfentry 2>&1 | FileCheck --check-prefix=ERR %s
// ERR: error: unsupported option '-mfentry' for target 'powerpc64le'
// FP: "-mframe-pointer=all"
// NOFP: "-mframe-pointer=none"
void foo(void) {}