[PATCH] D19813: Move "Eliminate Available Externally" immediately after the inliner

[Mehdi AMINI via llvm-commits]

joker.eph created this revision.
joker.eph added a reviewer: chandlerc.
joker.eph added a subscriber: llvm-commits.
Herald added a subscriber: joker.eph.

This pass is supposed to reduce the size of the IR for compile time
purpose. We should run it ASAP.

http://reviews.llvm.org/D19813

Files:
  lib/Transforms/IPO/PassManagerBuilder.cpp
  test/Other/pass-pipelines.ll

Index: test/Other/pass-pipelines.ll
===================================================================
--- test/Other/pass-pipelines.ll
+++ test/Other/pass-pipelines.ll
@@ -55,7 +55,10 @@
 ; Next we break out of the main Function passes inside the CGSCC pipeline with
 ; a barrier pass.
 ; CHECK-O2: A No-Op Barrier Pass
-; Inferring function attribute should be immediately after the CGSCC pipeline.
+; Reduce the size of the IR ASAP after the inliner.
+; CHECK-O2-NEXT: Eliminate Available Externally
+; Inferring function attribute should be right after the CGSCC pipeline, before
+; any other optimizations/analyses.
 ; CHECK-O2-NEXT: CallGraph
 ; CHECK-O2-NEXT: Deduce function attributes in RPO
 ; CHECK-O2-NOT: Manager
Index: lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- lib/Transforms/IPO/PassManagerBuilder.cpp
+++ lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -404,6 +404,18 @@
   // we must insert a no-op module pass to reset the pass manager.
   MPM.add(createBarrierNoopPass());
 
+  if (!DisableUnitAtATime && OptLevel > 1 && !PrepareForLTO)
+    // Remove avail extern fns and globals definitions if we aren't
+    // compiling an object file for later LTO. For LTO we want to preserve
+    // these so they are eligible for inlining at link-time. Note if they
+    // are unreferenced they will be removed by GlobalDCE later, so
+    // this only impacts referenced available externally globals.
+    // Eventually they will be suppressed during codegen, but eliminating
+    // here enables more opportunity for GlobalDCE as it may make
+    // globals referenced by available external functions dead
+    // and saves running remaining passes on the eliminated functions.
+    MPM.add(createEliminateAvailableExternallyPass());
+
   if (!DisableUnitAtATime)
     MPM.add(createReversePostOrderFunctionAttrsPass());
 
@@ -428,18 +440,6 @@
     MPM.add(createLICMPass());                  // Hoist loop invariants
   }
 
-  if (!DisableUnitAtATime && OptLevel > 1 && !PrepareForLTO)
-    // Remove avail extern fns and globals definitions if we aren't
-    // compiling an object file for later LTO. For LTO we want to preserve
-    // these so they are eligible for inlining at link-time. Note if they
-    // are unreferenced they will be removed by GlobalDCE later, so
-    // this only impacts referenced available externally globals.
-    // Eventually they will be suppressed during codegen, but eliminating
-    // here enables more opportunity for GlobalDCE as it may make
-    // globals referenced by available external functions dead
-    // and saves running remaining passes on the eliminated functions.
-    MPM.add(createEliminateAvailableExternallyPass());
-
   if (PerformThinLTO) {
     // Remove dead fns and globals. Removing unreferenced functions could lead
     // to more opportunities for globalopt.


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