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[llvm] Set the default for -bbsections-cold-text-prefix to .text.split. 

After using this for a while, we find that it is generally useful to
have it set to .text.split. by default, removing the need for an
additional -mllvm option.

Differential Revision: https://reviews.llvm.org/D88997
This commit is contained in:
Snehasish Kumar 2020-10-07 11:42:02 -07:00
parent adfb541501
commit 77638a5343
6 changed files with 14 additions and 14 deletions
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6
llvm/lib/CodeGen/BasicBlockSections.cpp
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@ -81,12 +81,12 @@ using namespace llvm;
// Placing the cold clusters in a separate section mitigates against poor
// profiles and allows optimizations such as hugepage mapping to be applied at a
// section granularity. Where necessary, users should set this to ".text.split."
// which is recognized by lld via the `-z keep-text-section-prefix` flag.
// section granularity. Defaults to ".text.split." which is recognized by lld
// via the `-z keep-text-section-prefix` flag.
cl::opt<std::string> llvm::BBSectionsColdTextPrefix(
"bbsections-cold-text-prefix",
cl::desc("The text prefix to use for cold basic block clusters"),
cl::init(".text.unlikely."), cl::Hidden);
cl::init(".text.split."), cl::Hidden);
namespace {

2
llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
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@ -867,7 +867,7 @@ MCSection *TargetLoweringObjectFileELF::getSectionForMachineBasicBlock(
assert(MBB.isBeginSection() && "Basic block does not start a section!");
unsigned UniqueID = MCContext::GenericSectionID;
// For cold sections use the .text.unlikely prefix along with the parent
// For cold sections use the .text.split. prefix along with the parent
// function name. All cold blocks for the same function go to the same
// section. Similarly all exception blocks are grouped by symbol name
// under the .text.eh prefix. For regular sections, we either use a unique

2
llvm/test/CodeGen/X86/basic-block-sections-clusters-branches.ll
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@ -50,7 +50,7 @@ declare i32 @baz() #1
; LINUX-SECTIONS1: .section .text.foo,"ax",@progbits,unique,1
; LINUX-SECTIONS1-LABEL: foo.1:
; LINUX-SECTIONS1: jmp foo.cold
; LINUX-SECTIONS1: .section .text.unlikely.foo,"ax",@progbits
; LINUX-SECTIONS1: .section .text.split.foo,"ax",@progbits
; LINUX-SECTIONS1-LABEL: foo.cold:
; LINUX-SECTIONS2: .section .text.foo,"ax",@progbits

2
llvm/test/CodeGen/X86/basic-block-sections-clusters.ll
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@ -50,7 +50,7 @@ declare i32 @baz() #1
; LINUX-SECTIONS1-LABEL: .LBB_END0_1:
; LINUX-SECTIONS1-NEXT: .size foo.1, .LBB_END0_1-foo.1
; LINUX-SECTIONS1-NOT: .section
; LINUX-SECTIONS1: .section .text.unlikely.foo,"ax",@progbits
; LINUX-SECTIONS1: .section .text.split.foo,"ax",@progbits
; LINUX-SECTIONS1-LABEL: foo.cold:
; LINUX-SECTIONS1-LABEL: .LBB_END0_3:
; LINUX-SECTIONS1-NEXT: .size foo.cold, .LBB_END0_3-foo.cold

6
llvm/test/CodeGen/X86/basic-block-sections-cold.ll
View File

@ -3,7 +3,7 @@
; RUN: echo '!_Z3bazb' > %t
; RUN: echo '!!0' >> %t
; RUN: llc < %s -mtriple=x86_64 -function-sections -basic-block-sections=%t -unique-basic-block-section-names | FileCheck %s -check-prefix=LINUX-SECTIONS
; RUN: llc < %s -mtriple=x86_64 -function-sections -basic-block-sections=%t -unique-basic-block-section-names -bbsections-cold-text-prefix=".text.split." | FileCheck %s -check-prefix=LINUX-SPLIT
; RUN: llc < %s -mtriple=x86_64 -function-sections -basic-block-sections=%t -unique-basic-block-section-names -bbsections-cold-text-prefix=".text.unlikely." | FileCheck %s -check-prefix=LINUX-SPLIT
define void @_Z3bazb(i1 zeroext %0) nounwind {
br i1 %0, label %2, label %4
@ -29,13 +29,13 @@ declare i32 @_Z3foov() #1
; Check that the basic block with id 1 doesn't get a section.
; LINUX-SECTIONS-NOT: .section .text._Z3bazb._Z3bazb.1,"ax",@progbits,unique
; Check that a single cold section is started here and id 1 and 2 blocks are placed here.
; LINUX-SECTIONS: .section .text.unlikely._Z3bazb,"ax",@progbits
; LINUX-SECTIONS: .section .text.split._Z3bazb,"ax",@progbits
; LINUX-SECTIONS: _Z3bazb.cold:
; LINUX-SECTIONS-NOT: .section .text._Z3bazb._Z3bazb.2,"ax",@progbits,unique
; LINUX-SECTIONS: .LBB0_2:
; LINUX-SECTIONS: .size _Z3bazb, .Lfunc_end{{[0-9]}}-_Z3bazb
; LINUX-SPLIT: .section .text.split._Z3bazb,"ax",@progbits
; LINUX-SPLIT: .section .text.unlikely._Z3bazb,"ax",@progbits
; LINUX-SPLIT-NEXT: _Z3bazb.cold:
; LINUX-SPLIT-NEXT: callq _Z3barv
; LINUX-SPLIT: .LBB0_2:

10
llvm/test/CodeGen/X86/machine-function-splitter.ll
View File

@ -3,9 +3,9 @@
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -split-machine-functions -mfs-psi-cutoff=950000 | FileCheck %s -check-prefix=MFS-OPTS2
define void @foo1(i1 zeroext %0) nounwind !prof !14 !section_prefix !15 {
;; Check that cold block is moved to .text.unlikely.
;; Check that cold block is moved to .text.split.
; MFS-DEFAULTS-LABEL: foo1
; MFS-DEFAULTS: .section .text.unlikely.foo1
; MFS-DEFAULTS: .section .text.split.foo1
; MFS-DEFAULTS-NEXT: foo1.cold:
; MFS-DEFAULTS-NOT: callq bar
; MFS-DEFAULTS-NEXT: callq baz
@ -65,7 +65,7 @@ define void @foo3(i1 zeroext %0) nounwind !section_prefix !15 {
define void @foo4(i1 zeroext %0, i1 zeroext %1) nounwind !prof !20 {
;; Check that count threshold works.
; MFS-OPTS1-LABEL: foo4
; MFS-OPTS1: .section .text.unlikely.foo4
; MFS-OPTS1: .section .text.split.foo4
; MFS-OPTS1-NEXT: foo4.cold:
; MFS-OPTS1-NOT: callq bar
; MFS-OPTS1-NOT: callq baz
@ -99,7 +99,7 @@ define void @foo4(i1 zeroext %0, i1 zeroext %1) nounwind !prof !20 {
define void @foo5(i1 zeroext %0, i1 zeroext %1) nounwind !prof !20 {
;; Check that profile summary info cutoff works.
; MFS-OPTS2-LABEL: foo5
; MFS-OPTS2: .section .text.unlikely.foo5
; MFS-OPTS2: .section .text.split.foo5
; MFS-OPTS2-NEXT: foo5.cold:
; MFS-OPTS2-NOT: callq bar
; MFS-OPTS2-NOT: callq baz
@ -152,7 +152,7 @@ define void @foo6(i1 zeroext %0) nounwind section "nosplit" !prof !14 {
define i32 @foo7(i1 zeroext %0) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) !prof !14 {
;; Check that cold ehpads are not split out.
; MFS-DEFAULTS-LABEL: foo7
; MFS-DEFAULTS: .section .text.unlikely.foo7,"ax",@progbits
; MFS-DEFAULTS: .section .text.split.foo7,"ax",@progbits
; MFS-DEFAULTS-NEXT: foo7.cold:
; MFS-DEFAULTS-NOT: callq _Unwind_Resume
; MFS-DEFAULTS: callq baz