[PATCH] D20586: IRLinker: fix double scheduling of mapping a global value because of an alias
Mehdi AMINI via llvm-commits
llvm-commits at lists.llvm.org
Tue May 24 11:56:51 PDT 2016
joker.eph created this revision.
joker.eph added reviewers: rafael, dexonsmith.
joker.eph added a subscriber: llvm-commits.
This test was hitting an assertion in the value mapper because
the IRLinker was trying to map two times @A while materializing
the initializer for @C.
Fix http://llvm.org/PR27850
http://reviews.llvm.org/D20586
Files:
lib/Linker/IRMover.cpp
test/Linker/alias-3.ll
Index: test/Linker/alias-3.ll
===================================================================
--- /dev/null
+++ test/Linker/alias-3.ll
@@ -0,0 +1,13 @@
+; RUN: llvm-link %s -S -o - | FileCheck %s
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9"
+
+; CHECK-DAG: @A = internal constant i8 1
+; CHECK-DAG: @B = alias i8, i8* @A
+; CHECK-DAG: @C = global [2 x i8*] [i8* @A, i8* @B]
+
+ at A = internal constant i8 1
+ at B = alias i8, i8* @A
+ at C = global [2 x i8*] [i8* @A, i8* @B]
+
+
Index: lib/Linker/IRMover.cpp
===================================================================
--- lib/Linker/IRMover.cpp
+++ lib/Linker/IRMover.cpp
@@ -557,6 +557,17 @@
return;
}
+ // When linking a global for an alias, it will always be linked. However we
+ // need to check if it was not already scheduled to satify a reference from a
+ // regular global value initializer. We know if it has been schedule if the
+ // "New" GlobalValue that is mapped here for the alias is the same as the one
+ // already mapped. If there is an entry in the ValueMap but the value is
+ // different, it means that the value already had a definition in the
+ // destination module (linkonce for instance), but we need a new definition
+ // for the alias ("New" will be different.
+ if (ForAlias && ValueMap.lookup(Old) == New)
+ return;
+
if (ForAlias || shouldLink(New, *Old))
linkGlobalValueBody(*New, *Old);
}
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