[LTO] Fix the issue of resetting the triple to default when it's empty

[fzou1]

The empty triple is passed to lookupTarget function and it's not set to default one. This issue is exposed after changes in #157591.

[llvmbot]

@llvm/pr-subscribers-lto

Author: Feng Zou (fzou1)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/157829.diff

1 Files Affected:

• (modified) llvm/lib/LTO/LTOCodeGenerator.cpp (+3-2)

diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index cdeab98ff6c98..8ea4e530dc3eb 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -377,8 +377,9 @@ bool LTOCodeGenerator::determineTarget() {
 
   TripleStr = MergedModule->getTargetTriple().str();
   llvm::Triple Triple(TripleStr);
-  if (TripleStr.empty()) {
-    TripleStr = sys::getDefaultTargetTriple();
+  if (Triple.empty()) {
+    Triple = llvm::Triple(sys::getDefaultTargetTriple());
+    TripleStr = Triple.getTriple();
     MergedModule->setTargetTriple(Triple);
   }
 

[arsenm]

Testcase?

[fzou1]

Testcase?

I added a test case for this issue.

[arsenm]

Suggested change

	; CHECK-NOT: llvm-lto: error: No available targets are compatible with triple ""
	; CHECK-NOT: error

[arsenm]

Alternatively there's not much gained by checking stderr, since it's not exiting 1 anymore. If you want to check something, that the output is valid might be better

[fzou1]

Alternatively there's not much gained by checking stderr, since it's not exiting 1 anymore. If you want to check something, that the output is valid might be better

Updated test to check the symbol if the output is valid.

[arsenm]

This is in the X86 subdirectory, but I don't see where X86 use would come from. This is the odd case where "generic" target tests might be appropriate. Can you move this to the parent directory?

[fzou1]

Done.

[arsenm]

Suggested change

	; RUN: llvm-lto -o %t2 %t1 2>&1 | FileCheck --allow-empty %s
	; RUN: llvm-lto -o /dev/null %t1 2>&1 | FileCheck --allow-empty %s

[arsenm]

Could also rewrite this to avoid constructing the wrong triple to start with

[fzou1]

Updated. Thanks.