[llvm] [llvm][ELF] Correctly set the .llvm.lto section type (PR #92820)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Paul Kirth (ilovepi)

<details>
<summary>Changes</summary>

Support for the SHT_LLVM_LTO section type was added in
https://github.com/llvm/llvm-project/commit/a484e020d75d398049e1fcbeb0157d57011714b3,
but the `.llvm.lto` section type was never set. This patch sets the ELF
section type to SHT_LLVM_LTO for sections with a `.llvm.lto` prefix, which
should only be emitted when using FatLTO.


---
Full diff: https://github.com/llvm/llvm-project/pull/92820.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp (+3) 
- (modified) llvm/test/CodeGen/X86/fat-lto-section.ll (+1-1) 


``````````diff
diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3e1897ce670a6..567e9443759f1 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -527,6 +527,9 @@ static unsigned getELFSectionType(StringRef Name, SectionKind K) {
   if (K.isBSS() || K.isThreadBSS())
     return ELF::SHT_NOBITS;
 
+  if(hasPrefix(Name, ".llvm.lto"))
+    return ELF::SHT_LLVM_LTO;
+
   return ELF::SHT_PROGBITS;
 }
 
diff --git a/llvm/test/CodeGen/X86/fat-lto-section.ll b/llvm/test/CodeGen/X86/fat-lto-section.ll
index 30c56229a0e2a..f3ca8436affb4 100644
--- a/llvm/test/CodeGen/X86/fat-lto-section.ll
+++ b/llvm/test/CodeGen/X86/fat-lto-section.ll
@@ -5,6 +5,6 @@
 ; RUN:   | FileCheck %s --check-prefix=EXCLUDE
 
 ; EXCLUDE: Name               Type     {{.*}} ES Flg Lk Inf Al
-; EXCLUDE: .llvm.lto          PROGBITS {{.*}} 00   E  0   0  1
+; EXCLUDE: .llvm.lto          LLVM_LTO {{.*}} 00   E  0   0  1
 
 @a = global i32 1

``````````

</details>


https://github.com/llvm/llvm-project/pull/92820