[llvm-branch-commits] [LTO] Enable PrepareForLTO in pre-link pipelines (PR #229151)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Aiden Grossman (boomanaiden154)

<details>
<summary>Changes</summary>

This reverts 272ad5da54a63a16312e8c3ba0de4290d4931002. This should not
have any impact on CodeGeneration given PrepareForLTO is now a no-op
currently in LoopUnroll. This just gets the plumbing done for some
future planned uses around respecting pragmas.

This also pulls in changes from #<!-- -->219604 to be complete.


---
Full diff: https://github.com/llvm/llvm-project/pull/229151.diff


2 Files Affected:

- (modified) llvm/include/llvm/Transforms/Scalar/LoopUnrollPass.h (+2-2) 
- (modified) llvm/lib/Passes/PassBuilderPipelines.cpp (+6-3) 


``````````diff
diff --git a/llvm/include/llvm/Transforms/Scalar/LoopUnrollPass.h b/llvm/include/llvm/Transforms/Scalar/LoopUnrollPass.h
index ea2d8576d15cb..328a027bbb553 100644
--- a/llvm/include/llvm/Transforms/Scalar/LoopUnrollPass.h
+++ b/llvm/include/llvm/Transforms/Scalar/LoopUnrollPass.h
@@ -88,9 +88,9 @@ struct LoopUnrollOptions {
   bool PrepareForLTO = false;
 
   LoopUnrollOptions(int OptLevel = 2, bool OnlyWhenForced = false,
-                    bool ForgetSCEV = false)
+                    bool ForgetSCEV = false, bool PrepareForLTO = false)
       : OptLevel(OptLevel), OnlyWhenForced(OnlyWhenForced),
-        ForgetSCEV(ForgetSCEV) {}
+        ForgetSCEV(ForgetSCEV), PrepareForLTO(PrepareForLTO) {}
 
   /// Enables or disables partial unrolling. When disabled only full unrolling
   /// is allowed.
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index bd37fffc8e991..85a854b6584cb 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -577,7 +577,8 @@ PassBuilder::buildO1FunctionSimplificationPipeline(OptimizationLevel Level,
       PGOOpt->Action != PGOOptions::SampleUse)
     LPM2.addPass(LoopFullUnrollPass(static_cast<int>(Level),
                                     /* OnlyWhenForced= */ !PTO.LoopUnrolling,
-                                    PTO.ForgetAllSCEVInLoopUnroll));
+                                    PTO.ForgetAllSCEVInLoopUnroll,
+                                    /*PrepareForLTO=*/isLTOPreLink(Phase)));
 
   invokeLoopOptimizerEndEPCallbacks(LPM2, Level);
 
@@ -759,7 +760,8 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
       PGOOpt->Action != PGOOptions::SampleUse)
     LPM2.addPass(LoopFullUnrollPass(static_cast<int>(Level),
                                     /* OnlyWhenForced= */ !PTO.LoopUnrolling,
-                                    PTO.ForgetAllSCEVInLoopUnroll));
+                                    PTO.ForgetAllSCEVInLoopUnroll,
+                                    /*PrepareForLTO=*/isLTOPreLink(Phase)));
 
   invokeLoopOptimizerEndEPCallbacks(LPM2, Level);
 
@@ -1477,7 +1479,8 @@ void PassBuilder::addVectorPasses(OptimizationLevel Level,
     }
     FPM.addPass(LoopUnrollPass(LoopUnrollOptions(
         static_cast<int>(Level), /*OnlyWhenForced=*/!PTO.LoopUnrolling,
-        PTO.ForgetAllSCEVInLoopUnroll)));
+        PTO.ForgetAllSCEVInLoopUnroll,
+        /*PrepareForLTO=*/isLTOPreLink(LTOPhase))));
     FPM.addPass(WarnMissedTransformationsPass());
     // Now that we are done with loop unrolling, be it either by LoopVectorizer,
     // or LoopUnroll passes, some variable-offset GEP's into alloca's could have

``````````

</details>


https://github.com/llvm/llvm-project/pull/229151