[PATCH] D26194: [3.9.1] Port "[ThinLTO] Disable importing and other cross-module optis at -O0"

[Teresa Johnson via llvm-commits]

tejohnson created this revision.
tejohnson added a reviewer: pcc.
tejohnson added subscribers: llvm-commits, mehdi_amini, johanengelen.

There is no point to importing at -O0, since we won't inline. We should
also disable other cross-module optimizations.

This change avoids 3.9 bug PR30774, which is due to the old DIGlobalVariable
references to GlobalVariable, and only at -O0 since the dangling
reference to a non-imported variable is not cleaned up. This is the
simplest workaround for the issue, which was addressed by reversing the
DIGlobalVariable to GlobalVariable edges (r281284).

Fixes PR30774.


https://reviews.llvm.org/D26194

Files:
  test/tools/gold/X86/Inputs/thinlto_funcimport.ll
  test/tools/gold/X86/thinlto_funcimport.ll
  tools/gold/gold-plugin.cpp

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