[PATCH] D59080: Merge of global constants does not happen when constants have common linkage

[Ramakota Reddy via Phabricator via llvm-commits]

ramred01 updated this revision to Diff 192597.
ramred01 retitled this revision from "Merge of global constants not happenning" to "Merge of global constants does not happen when constants have common linkage".
ramred01 edited the summary of this revision.
ramred01 added a subscriber: llvm-commits.
ramred01 added a comment.
Herald added a subscriber: javed.absar.

Updated the summary.

Added a test case.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59080/new/

https://reviews.llvm.org/D59080

Files:
  include/llvm/IR/GlobalAlias.h
  lib/CodeGen/AsmPrinter/AsmPrinter.cpp
  lib/CodeGen/GlobalMerge.cpp
  test/CodeGen/AArch64/global_merge_ac6_aarch64.ll


Index: test/CodeGen/AArch64/global_merge_ac6_aarch64.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/global_merge_ac6_aarch64.ll
@@ -0,0 +1,33 @@
+;RUN: llc -O3 %s -o - -verify-machineinstrs | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64-arm-none-eabi"
+
+ at global0 = common dso_local local_unnamed_addr global i32 0, align 4
+ at global1 = common dso_local local_unnamed_addr global i32 0, align 4
+
+; Function Attrs: norecurse nounwind readonly
+;CHECK-LABEL: @func
+;CHECK: adrp
+;CHECK-NEXT: add
+;CHECK-NEXT: ldp
+;CHECK-NEXT: add
+;CHECK-NEXT: ret
+define dso_local i32 @func() local_unnamed_addr #0 {
+  %1 = load i32, i32* @global0, align 4, !tbaa !2
+  %2 = load i32, i32* @global1, align 4, !tbaa !2
+  %3 = add nsw i32 %2, %1
+  ret i32 %3
+}
+
+attributes #0 = { norecurse nounwind readonly "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+neon" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!llvm.ident = !{!1}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{!"clang version 9.0.0 (https://git.llvm.org/git/clang.git/ 112a7a3c34df3dc506b52cd89e155287cdbcea55) (https://git.llvm.org/git/llvm.git/ feeb3cebe7a586a8e1b12735024389dd8d3bab53)"}
+!2 = !{!3, !3, i64 0}
+!3 = !{!"int", !4, i64 0}
+!4 = !{!"omnipotent char", !5, i64 0}
+!5 = !{!"Simple C/C++ TBAA"}
Index: lib/CodeGen/GlobalMerge.cpp
===================================================================
--- lib/CodeGen/GlobalMerge.cpp
+++ lib/CodeGen/GlobalMerge.cpp
@@ -616,8 +616,8 @@
     if (TM && !TM->shouldAssumeDSOLocal(M, &GV))
       continue;
 
-    if (!(MergeExternalGlobals && GV.hasExternalLinkage()) &&
-        !GV.hasInternalLinkage())
+    if (!(MergeExternalGlobals && GV.hasExternalLinkage())&&
+        !GV.hasInternalLinkage() && !GV.hasCommonLinkage())
       continue;
 
     PointerType *PT = dyn_cast<PointerType>(GV.getType());
Index: lib/CodeGen/AsmPrinter/AsmPrinter.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1330,12 +1330,14 @@
                                           const GlobalIndirectSymbol& GIS) {
   MCSymbol *Name = getSymbol(&GIS);
 
-  if (GIS.hasExternalLinkage() || !MAI->getWeakRefDirective())
+  if (GIS.hasExternalLinkage() || GIS.hasCommonLinkage() ||
+      !MAI->getWeakRefDirective())
     OutStreamer->EmitSymbolAttribute(Name, MCSA_Global);
   else if (GIS.hasWeakLinkage() || GIS.hasLinkOnceLinkage())
     OutStreamer->EmitSymbolAttribute(Name, MCSA_WeakReference);
   else
-    assert(GIS.hasLocalLinkage() && "Invalid alias or ifunc linkage");
+    assert((GIS.hasLocalLinkage()) &&
+           "Invalid alias or ifunc linkage");
 
   // Set the symbol type to function if the alias has a function type.
   // This affects codegen when the aliasee is not a function.
Index: include/llvm/IR/GlobalAlias.h
===================================================================
--- include/llvm/IR/GlobalAlias.h
+++ include/llvm/IR/GlobalAlias.h
@@ -83,7 +83,8 @@
 
   static bool isValidLinkage(LinkageTypes L) {
     return isExternalLinkage(L) || isLocalLinkage(L) ||
-      isWeakLinkage(L) || isLinkOnceLinkage(L);
+      isWeakLinkage(L) || isLinkOnceLinkage(L) || 
+      isCommonLinkage(L);
   }
 
   // Methods for support type inquiry through isa, cast, and dyn_cast:


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