[PATCH] D133456: [V2] MC: make section classification a bit more thorough

[Saleem Abdulrasool via Phabricator via llvm-commits]

compnerd updated this revision to Diff 461959.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D133456/new/

https://reviews.llvm.org/D133456

Files:
  llvm/lib/MC/MCContext.cpp
  llvm/test/MC/ELF/section-classification.ll


Index: llvm/test/MC/ELF/section-classification.ll
===================================================================
--- /dev/null
+++ llvm/test/MC/ELF/section-classification.ll
@@ -0,0 +1,15 @@
+; We run this test explicitly converting from `.ll` to `.s` to `.o` to test the
+; classification of the section and the incorrect handling for the padding flag.
+
+; RUN: llc -filetype asm -o - %s | llvm-mc -triple x86_64-unknown-linux-gnu -filetype obj -o /dev/null -
+; REQUIRES: asserts
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.C = type { i32 }
+
+$_ZZ6getRefvE8instance = comdat any
+
+ at _ZZ6getRefvE8instance = linkonce_odr dso_local global %struct.C zeroinitializer, comdat, align 4
+ at llvm.compiler.used = appending global [1 x ptr] [ptr @_ZZ6getRefvE8instance], section "llvm.metadata"
Index: llvm/lib/MC/MCContext.cpp
===================================================================
--- llvm/lib/MC/MCContext.cpp
+++ llvm/lib/MC/MCContext.cpp
@@ -564,8 +564,37 @@
     Kind = SectionKind::getExecuteOnly();
   else if (Flags & ELF::SHF_EXECINSTR)
     Kind = SectionKind::getText();
-  else
+  else if (~Flags & ELF::SHF_WRITE)
     Kind = SectionKind::getReadOnly();
+  else if (Flags & ELF::SHF_TLS)
+    Kind = (Type & ELF::SHT_NOBITS) ? SectionKind::getThreadBSS()
+                                    : SectionKind::getThreadData();
+  else
+    // Default to `SectionKind::getText()`. This is the default for gas as
+    // well. The condition that falls into this case is where we do not have any
+    // section flags and must infer a classification rather than where we have
+    // section flags (i.e. this is not that SHF_EXECINSTR is unset bur rather it
+    // is unknown).
+    Kind = llvm::StringSwitch<SectionKind>(CachedName)
+               .Case(".bss", SectionKind::getBSS())
+               .StartsWith(".bss.", SectionKind::getBSS())
+               .StartsWith(".gnu.linkonce.b.", SectionKind::getBSS())
+               .StartsWith(".llvm.linkonce.b.", SectionKind::getBSS())
+               .Case(".data", SectionKind::getData())
+               .Case(".data1", SectionKind::getData())
+               .Case(".data.rel.ro", SectionKind::getReadOnlyWithRel())
+               .Case(".rodata", SectionKind::getReadOnly())
+               .Case(".rodata1", SectionKind::getReadOnly())
+               .Case(".tbss", SectionKind::getThreadBSS())
+               .StartsWith(".tbss.", SectionKind::getThreadData())
+               .StartsWith(".gnu.linkonce.tb.", SectionKind::getThreadData())
+               .StartsWith(".llvm.linkonce.tb.", SectionKind::getThreadData())
+               .Case(".tdata", SectionKind::getThreadData())
+               .StartsWith(".tdata.", SectionKind::getThreadData())
+               .StartsWith(".gnu.linkonce.td.", SectionKind::getThreadData())
+               .StartsWith(".llvm.linkonce.td.", SectionKind::getThreadData())
+               .StartsWith(".debug_", SectionKind::getMetadata())
+               .Default(SectionKind::getText());
 
   MCSectionELF *Result =
       createELFSectionImpl(CachedName, Type, Flags, Kind, EntrySize, GroupSym,


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