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PMB: Add an importing WPD pass to the start of the ThinLTO backend pipeline. 

Differential Revision: https://reviews.llvm.org/D30008

llvm-svn: 295260
This commit is contained in:
Peter Collingbourne 2017-02-15 23:48:38 +00:00
parent 3963ba3e48
commit 08eb081ac3
1 changed files with 15 additions and 1 deletions
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16
llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
View File

@ -830,8 +830,22 @@ void PassManagerBuilder::populateThinLTOPassManager(
if (VerifyInput)
PM.add(createVerifierPass());
if (Summary)
if (Summary) {
// These passes import type identifier resolutions for whole-program
// devirtualization and CFI. They must run early because other passes may
// disturb the specific instruction patterns that these passes look for,
// creating dependencies on resolutions that may not appear in the summary.
//
// For example, GVN may transform the pattern assume(type.test) appearing in
// two basic blocks into assume(phi(type.test, type.test)), which would
// transform a dependency on a WPD resolution into a dependency on a type
// identifier resolution for CFI.
//
// Also, WPD has access to more precise information than ICP and can
// devirtualize more effectively, so it should operate on the IR first.
PM.add(createWholeProgramDevirtPass(PassSummaryAction::Import, Summary));
PM.add(createLowerTypeTestsPass(PassSummaryAction::Import, Summary));
}
populateModulePassManager(PM);