[llvm] r371643 - [IRMover] Don't map globals if their types are the same

Wed Sep 11 11:35:49 PDT 2019

Author: pirama
Date: Wed Sep 11 11:35:49 2019
New Revision: 371643

URL: http://llvm.org/viewvc/llvm-project?rev=371643&view=rev
Log:
[IRMover] Don't map globals if their types are the same

Summary:
During IR Linking, if the types of two globals in destination and source
modules are the same, it can only be because the global in the
destination module is originally from the source module and got added to
the destination module from a shared metadata.

We shouldn't map this type to itself in case the type's components get
remapped to a new type from the destination (for instance, during the
loop over SrcM->getIdentifiedStructTypes() further below in
IRLinker::computeTypeMapping()).

Fixes PR40312.

Reviewers: tejohnson, pcc, srhines

Subscribers: mehdi_amini, hiraditya, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66814

Added:
    llvm/trunk/test/LTO/X86/Inputs/type-mapping-bug3.ll
    llvm/trunk/test/LTO/X86/type-mapping-bug3.ll
Modified:
    llvm/trunk/lib/Linker/IRMover.cpp

Modified: llvm/trunk/lib/Linker/IRMover.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Linker/IRMover.cpp?rev=371643&r1=371642&r2=371643&view=diff
==============================================================================

--- llvm/trunk/lib/Linker/IRMover.cpp (original)
+++ llvm/trunk/lib/Linker/IRMover.cpp Wed Sep 11 11:35:49 2019
@@ -758,8 +758,18 @@ void IRLinker::computeTypeMapping() {
   }
 
   for (GlobalValue &SGV : *SrcM)
-    if (GlobalValue *DGV = getLinkedToGlobal(&SGV))
+    if (GlobalValue *DGV = getLinkedToGlobal(&SGV)) {
+      if (DGV->getType() == SGV.getType()) {
+        // If the types of DGV and SGV are the same, it means that DGV is from
+        // the source module and got added to DstM from a shared metadata.  We
+        // shouldn't map this type to itself in case the type's components get
+        // remapped to a new type from DstM (for instance, during the loop over
+        // SrcM->getIdentifiedStructTypes() below).
+        continue;
+      }
+
       TypeMap.addTypeMapping(DGV->getType(), SGV.getType());
+    }
 
   for (GlobalValue &SGV : SrcM->aliases())
     if (GlobalValue *DGV = getLinkedToGlobal(&SGV))

Added: llvm/trunk/test/LTO/X86/Inputs/type-mapping-bug3.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/LTO/X86/Inputs/type-mapping-bug3.ll?rev=371643&view=auto
==============================================================================
--- llvm/trunk/test/LTO/X86/Inputs/type-mapping-bug3.ll (added)
+++ llvm/trunk/test/LTO/X86/Inputs/type-mapping-bug3.ll Wed Sep 11 11:35:49 2019
@@ -0,0 +1,26 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; T2 is the non-opaque struct required to trigger the uniqued T2.0 and T3.0 to
+; respectively T2 and T3 in the destination module.
+%"T2" = type { %"T3"* }
+%"T3" = type opaque
+
+; Use/refer to T2 so it gets added as an IdentifiedStructType.  The debug
+; reference to !6 is required to transitively load the metadata !5.
+define void @a(%"T2") !dbg !6 {
+  ret void
+}
+
+!llvm.module.flags = !{!0, !1}
+!llvm.dbg.cu = !{!2}
+!0 = !{i32 1, !"ThinLTO", i32 0}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, retainedTypes: !4)
+!3 = !DIFile(filename: "f2", directory: "")
+!4 = !{!5}
+
+; This DICompositeType refers to !5 in type-mapping-bug3.ll
+!5 = !DICompositeType(tag: DW_TAG_structure_type, flags: DIFlagFwdDecl, identifier: "SHARED")
+
+!6 = distinct !DISubprogram(unit: !2)

Added: llvm/trunk/test/LTO/X86/type-mapping-bug3.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/LTO/X86/type-mapping-bug3.ll?rev=371643&view=auto
==============================================================================
--- llvm/trunk/test/LTO/X86/type-mapping-bug3.ll (added)
+++ llvm/trunk/test/LTO/X86/type-mapping-bug3.ll Wed Sep 11 11:35:49 2019
@@ -0,0 +1,47 @@
+; RUN: opt -module-summary -o %t0.o %S/Inputs/type-mapping-bug3.ll
+; RUN: opt -module-summary -o %t1.o %s
+; RUN: llvm-lto2 run -o %t2 %t0.o %t1.o -r %t0.o,a,px -r %t1.o,b,px -r %t1.o,c,px -r %t1.o,d,
+;
+; Test for the issue described in https://bugs.llvm.org/show_bug.cgi?id=40312
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; T2 is the non-opaque struct required to trigger the uniqued T2.0 and T3.0 to
+; respectively T2 and T3 in the destination module.
+%"T2" = type { %"T3"* }
+%"T3" = type opaque
+
+; Use/refer to T2 so it gets added as an IdentifiedStructType.
+define void @c(%"T2") {
+    unreachable
+}
+
+; The global declaration that causes the assertion when its type is mapped to
+; itself incorrectly.
+declare void @d(%"T3"*)
+
+define void @b() {
+entry:
+  %f.addr = alloca %"T3"*load %"T3"*, %"T3"** %f.addr
+
+  ; The call with the getCalledValue() vs getCalledFunction() mismatch.
+  call void @d(%"T3"* %0)
+  unreachable
+}
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!0, !1}
+!0 = !{i32 1, !"ThinLTO", i32 0}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, retainedTypes: !4)
+!3 = !DIFile(filename: "f1", directory: "")
+!4 = !{!5}
+
+; This DICompositeType is referenced by !5 in Inputs/type-mapping-bug3.ll
+; causing the function type in !7 to be added to its module.
+!5 = !DICompositeType(tag: DW_TAG_structure_type, templateParams: !6, identifier: "SHARED")
+!6 = !{!7}
+
+; The reference to d and T3 that gets loaded into %t0.o
+!7 = !DITemplateValueParameter(value: void (%"T3"*)* @d)


