Store GUIDs in metadatausers/orodley/guid-2

See https://discourse.llvm.org/t/rfc-keep-globalvalue-guids-stable/84801
for context.

This takes the existing AssignGUID pass from CtxProfAnalysis, and runs
it by default, at the appropriate stages of the LTO pipeline. It also
changes GlobalValue::getGUID() to retrieve the GUID from the metadata
instead of computing it.

We don't yet have the supporting downstream changes to make a dedicated
GUID table in bitcode, nor do we use the metadata as part of ThinLTO --
it retains its existing mechanisms of recomputing GUIDs from separately
saved data. That will be changed later.

1 files changed, 12 insertions, 3 deletions

diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 98821bb..0585303 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -130,6 +130,7 @@
 #include "llvm/Transforms/Scalar/TailRecursionElimination.h"
 #include "llvm/Transforms/Scalar/WarnMissedTransforms.h"
 #include "llvm/Transforms/Utils/AddDiscriminators.h"
+#include "llvm/Transforms/Utils/AssignGUID.h"
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
 #include "llvm/Transforms/Utils/CountVisits.h"
@@ -786,6 +787,7 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
 void PassBuilder::addRequiredLTOPreLinkPasses(ModulePassManager &MPM) {
   MPM.addPass(CanonicalizeAliasesPass());
   MPM.addPass(NameAnonGlobalPass());
+  MPM.addPass(AssignGUIDPass());
 }
 
 void PassBuilder::addPreInlinerPasses(ModulePassManager &MPM,
@@ -1234,9 +1236,6 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
     // In pre-link, we just want the instrumented IR. We use the contextual
     // profile in the post-thinlink phase.
     // The instrumentation will be removed in post-thinlink after IPO.
-    // FIXME(mtrofin): move AssignGUIDPass if there is agreement to use this
-    // mechanism for GUIDs.
-    MPM.addPass(AssignGUIDPass());
     if (IsCtxProfUse) {
       MPM.addPass(PGOCtxProfFlatteningPass(/*IsPreThinlink=*/true));
       return MPM;
@@ -1640,6 +1639,11 @@ PassBuilder::buildPerModuleDefaultPipeline(OptimizationLevel Level,
 
   ModulePassManager MPM;
 
+  /*
+  MPM.addPass(NameAnonGlobalPass());
+  MPM.addPass(AssignGUIDPass());
+  */
+
   // Convert @llvm.global.annotations to !annotation metadata.
   MPM.addPass(Annotation2MetadataPass());
 
@@ -2208,6 +2212,11 @@ PassBuilder::buildO0DefaultPipeline(OptimizationLevel Level,
 
   ModulePassManager MPM;
 
+  /*
+  MPM.addPass(NameAnonGlobalPass());
+  MPM.addPass(AssignGUIDPass());
+  */
+
   // Perform pseudo probe instrumentation in O0 mode. This is for the
   // consistency between different build modes. For example, a LTO build can be
   // mixed with an O0 prelink and an O2 postlink. Loading a sample profile in