[llvm-branch-commits] [llvm] 668da8c - [MC] Set the unique id of .stack_sizes to the associated .text section's

[Fangrui Song via llvm-branch-commits]

Author: Fangrui Song
Date: 2020-11-26T09:13:09-08:00
New Revision: 668da8c361fef5ada092534d4d20ea450831f6f6

URL: https://github.com/llvm/llvm-project/commit/668da8c361fef5ada092534d4d20ea450831f6f6
DIFF: https://github.com/llvm/llvm-project/commit/668da8c361fef5ada092534d4d20ea450831f6f6.diff

LOG: [MC] Set the unique id of .stack_sizes to the associated .text section's

Similar to D92113. Currently `clang -fstack-size-section -fno-unique-section-names`
sets the linked-to symbol to the first `.text`, which is:

* incorrect for COMDAT sections
* inferior for non-COMDAT sections in -ffunction-sections mode (poor --gc-sections: .stack_sizes cannot be separately discarded)

Note, if the section symbol can be referenced in more places (if the
function begin symbol does not apply), we probably should consider
defining a different BeginSymbol for sections with ",unique" linkage.

Reviewed By: grimar, jhenderson

Differential Revision: https://reviews.llvm.org/D92151

Added: 
    

Modified: 
    llvm/lib/MC/MCObjectFileInfo.cpp
    llvm/test/CodeGen/X86/stack-size-section-function-sections.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index b8c66c68f71c..75e65e3f10f4 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -997,7 +997,7 @@ MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
   }
 
   return Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, Flags, 0,
-                            GroupName, MCSection::NonUniqueID,
+                            GroupName, ElfSec.getUniqueID(),
                             cast<MCSymbolELF>(TextSec.getBeginSymbol()));
 }
 

diff  --git a/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll b/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll
index 3fb2fa97e775..92f312bd1185 100644
--- a/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll
+++ b/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll
@@ -1,14 +1,23 @@
-; RUN: llc < %s -mtriple=x86_64-linux -stack-size-section -function-sections | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-linux -stack-size-section -function-sections | \
+; RUN:   FileCheck %s --check-prefix=UNIQ
+; RUN: llc < %s -mtriple=x86_64-linux -stack-size-section -function-sections -unique-section-names=0 | \
+; RUN:   FileCheck %s --check-prefix=NOUNIQ
 
 ; Check we add SHF_LINK_ORDER for .stack_sizes and link it with the corresponding .text sections.
-; CHECK: .section        .text._Z3barv,"ax", at progbits
-; CHECK: .section        .stack_sizes,"o", at progbits,.text._Z3barv{{$}}
-; CHECK: .section        .text._Z3foov,"ax", at progbits
-; CHECK: .section        .stack_sizes,"o", at progbits,.text._Z3foov{{$}}
+; UNIQ:   .section        .text._Z3barv,"ax", at progbits{{$}}
+; UNIQ:   .section        .stack_sizes,"o", at progbits,.text._Z3barv{{$}}
+; UNIQ:   .section        .text._Z3foov,"ax", at progbits{{$}}
+; UNIQ:   .section        .stack_sizes,"o", at progbits,.text._Z3foov{{$}}
+; NOUNIQ: .section        .text,"ax", at progbits,unique,1
+; NOUNIQ: .section        .stack_sizes,"o", at progbits,.text,unique,1
+; NOUNIQ: .section        .text,"ax", at progbits,unique,2
+; NOUNIQ: .section        .stack_sizes,"o", at progbits,.text,unique,2
 
 ; Check we add .stack_size section to a COMDAT group with the corresponding .text section if such a COMDAT exists.
-; CHECK: .section        .text._Z4fooTIiET_v,"axG", at progbits,_Z4fooTIiET_v,comdat
-; CHECK: .section        .stack_sizes,"Go", at progbits,_Z4fooTIiET_v,comdat,.text._Z4fooTIiET_v{{$}}
+; UNIQ:   .section        .text._Z4fooTIiET_v,"axG", at progbits,_Z4fooTIiET_v,comdat{{$}}
+; UNIQ:   .section        .stack_sizes,"Go", at progbits,_Z4fooTIiET_v,comdat,.text._Z4fooTIiET_v{{$}}
+; NOUNIQ: .section        .text,"axG", at progbits,_Z4fooTIiET_v,comdat,unique,3
+; NOUNIQ: .section        .stack_sizes,"Go", at progbits,_Z4fooTIiET_v,comdat,.text,unique,3
 
 $_Z4fooTIiET_v = comdat any