[IRLinker] Don't add duplicate named MD node operand to dest module (#146020)

wenju-he · arsenm · web-flow · commit a6e870d0b6b8 · 2025-08-12T17:18:42.000+08:00
Fix llvm.ident exploding when linking many bitcode files in libclc. This should de-duplicate other named metadata as well, e.g. opencl.spir.version and opencl.ocl.version. This PR is a re-submit of https://reviews.llvm.org/D20582 (authored by Matt Arsenault) with update that only checks MD node pointer for duplication according to review comment in that PR. --------- Co-authored-by: Matt Arsenault <arsenm2@gmail.com>
diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
@@ -1133,8 +1133,11 @@ void IRLinker::linkNamedMDNodes() {
 
     NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());
     // Add Src elements into Dest node.
-    for (const MDNode *Op : NMD.operands())
-      DestNMD->addOperand(Mapper.mapMDNode(*Op));
+    for (const MDNode *Op : NMD.operands()) {
+      MDNode *MD = Mapper.mapMDNode(*Op);
+      if (!is_contained(DestNMD->operands(), MD))
+        DestNMD->addOperand(MD);
+    }
   }
 }
 
diff --git a/llvm/test/Linker/Inputs/ident.b.ll b/llvm/test/Linker/Inputs/ident.b.ll
@@ -1,2 +1,3 @@
-!llvm.ident = !{!0}
-!0 = !{!"Compiler V3"}
+!llvm.ident = !{!0, !1}
+!0 = !{!"Compiler V2"}
+!1 = !{!"Compiler V3"}
diff --git a/llvm/test/Linker/Inputs/opencl.md.a.ll b/llvm/test/Linker/Inputs/opencl.md.a.ll
@@ -0,0 +1,13 @@
+!llvm.module.flags = !{!0}
+!opencl.ocl.version = !{!1}
+!opencl.spir.version = !{!1}
+!opencl.used.extensions = !{!3, !4}
+!opencl.used.optional.core.features = !{!5}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 3, i32 0}
+!2 = !{!"LLVM.org clang version 20.1.0"}
+!3 = !{!"cl_images", !"cl_khr_fp16"}
+!4 = !{!"cl_images", !"cl_doubles"}
+!5 = !{!"cl_images"}
diff --git a/llvm/test/Linker/Inputs/opencl.md.b.ll b/llvm/test/Linker/Inputs/opencl.md.b.ll
@@ -0,0 +1,13 @@
+!llvm.module.flags = !{!0}
+!opencl.ocl.version = !{!1}
+!opencl.spir.version = !{!1}
+!opencl.used.extensions = !{!3, !4}
+!opencl.used.optional.core.features = !{!5}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 3, i32 0}
+!2 = !{!"LLVM.org clang version 20.1.0"}
+!3 = !{!"cl_images", !"cl_khr_fp16"}
+!4 = !{!"cl_khr_fp16", !"cl_doubles"}
+!5 = !{!"cl_images"}
diff --git a/llvm/test/Linker/Inputs/opencl.md.c.ll b/llvm/test/Linker/Inputs/opencl.md.c.ll
@@ -0,0 +1,6 @@
+!opencl.ocl.version = !{!0}
+!opencl.spir.version = !{!0}
+!llvm.ident = !{!1}
+
+!0 = !{i32 2, i32 0}
+!1 = !{!"LLVM.org clang version 20.1.0"}
diff --git a/llvm/test/Linker/dicompositetype-unique.ll b/llvm/test/Linker/dicompositetype-unique.ll
@@ -17,8 +17,8 @@
 
 ; Check that the type map will unique two DICompositeTypes.
 
-; CHECK:   !named = !{!0, !1, !2, !3, !0, !1, !2, !3}
-; NOMAP:   !named = !{!0, !1, !2, !3, !0, !4, !5, !6}
+; CHECK:   !named = !{!0, !1, !2, !3}
+; NOMAP:   !named = !{!0, !1, !2, !3, !4, !5, !6}
 !named = !{!0, !1, !2, !3}
 
 ; Check both directions.
diff --git a/llvm/test/Linker/distinct.ll b/llvm/test/Linker/distinct.ll
@@ -9,7 +9,7 @@
 ; Add an external reference to @global so that it gets linked in.
 @alias = alias i32, ptr @global
 
-; CHECK: !named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !0, !1, !2, !9, !10, !11, !12, !13, !14}
+; CHECK: !named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8, !9, !10, !11, !12, !13, !14}
 !named = !{!0, !1, !2, !3, !4, !5, !6, !7, !8}
 
 ; CHECK:      !0 = !{}
diff --git a/llvm/test/Linker/ident.ll b/llvm/test/Linker/ident.ll
@@ -1,6 +1,7 @@
 ; RUN: llvm-link %S/Inputs/ident.a.ll %S/Inputs/ident.b.ll -S | FileCheck %s
 
-; Verify that multiple input llvm.ident metadata are linked together.
+; Verify that multiple input llvm.ident metadata are linked together, and
+; duplicate "Compiler V2" metadata from the two inputs are unified.
 
 ; CHECK-DAG: !llvm.ident = !{!0, !1, !2}
 ; CHECK-DAG: "Compiler V1"
diff --git a/llvm/test/Linker/named-metadata-opencl-version.ll b/llvm/test/Linker/named-metadata-opencl-version.ll
@@ -0,0 +1,20 @@
+; RUN: llvm-link %S/Inputs/opencl.md.a.ll %S/Inputs/opencl.md.c.ll -S | FileCheck %s
+
+; OpenCL/SPIR version is different in input modules.
+; Verify that different OpenCL/SPIR version metadata nodes are kept in the
+; destination module.
+
+; CHECK: !opencl.ocl.version = !{![[#MD0:]], ![[#MD1:]]}
+; CHECK: !opencl.spir.version = !{![[#MD0]], ![[#MD1]]}
+; CHECK: !opencl.used.extensions = !{![[#MD2:]], ![[#MD3:]]}
+; CHECK: !opencl.used.optional.core.features = !{![[#MD4:]]}
+; CHECK: !llvm.ident = !{![[#MD5:]]}
+; CHECK: !llvm.module.flags = !{![[#MD6:]]}
+
+; CHECK: ![[#MD0]] = !{i32 3, i32 0}
+; CHECK: ![[#MD1]] = !{i32 2, i32 0}
+; CHECK: ![[#MD2]] = !{!"cl_images", !"cl_khr_fp16"}
+; CHECK: ![[#MD3]] = !{!"cl_images", !"cl_doubles"}
+; CHECK: ![[#MD4]] = !{!"cl_images"}
+; CHECK: ![[#MD5]] = !{!"LLVM.org clang version 20.1.0"}
+; CHECK: ![[#MD6]] = !{i32 1, !"wchar_size", i32 4}
diff --git a/llvm/test/Linker/named-metadata-opencl.ll b/llvm/test/Linker/named-metadata-opencl.ll
@@ -0,0 +1,18 @@
+; RUN: llvm-link %S/Inputs/opencl.md.a.ll %S/Inputs/opencl.md.b.ll -S | FileCheck %s
+
+; Verify that duplicate named metadata node isn't added to the result module.
+
+; CHECK: !opencl.ocl.version = !{![[#MD0:]]}
+; CHECK: !opencl.spir.version = !{![[#MD0]]}
+; CHECK: !opencl.used.extensions = !{![[#MD1:]], ![[#MD2:]], ![[#MD3:]]}
+; CHECK: !opencl.used.optional.core.features = !{![[#MD4:]]}
+; CHECK: !llvm.ident = !{![[#MD5:]]}
+; CHECK: !llvm.module.flags = !{![[#MD6:]]}
+
+; CHECK: ![[#MD0]] = !{i32 3, i32 0}
+; CHECK: ![[#MD1]] = !{!"cl_images", !"cl_khr_fp16"}
+; CHECK: ![[#MD2]] = !{!"cl_images", !"cl_doubles"}
+; CHECK: ![[#MD3]] = !{!"cl_khr_fp16", !"cl_doubles"}
+; CHECK: ![[#MD4]] = !{!"cl_images"}
+; CHECK: ![[#MD5]] = !{!"LLVM.org clang version 20.1.0"}
+; CHECK: ![[#MD6]] = !{i32 1, !"wchar_size", i32 4}
diff --git a/llvm/test/Linker/unique-fwd-decl-order.ll b/llvm/test/Linker/unique-fwd-decl-order.ll
@@ -8,7 +8,7 @@
 ; Note that these two assembly files number the nodes identically, even though
 ; the nodes are in a different order.  This is for the reader's convenience.
 
-; CHECK: !named = !{!0, !0}
+; CHECK: !named = !{!0}
 !named = !{!0}
 
 ; CHECK: !0 = !{!1}
diff --git a/llvm/test/ThinLTO/X86/import-metadata.ll b/llvm/test/ThinLTO/X86/import-metadata.ll
@@ -12,11 +12,12 @@
 
 ; CHECK: !llvm.dbg.cu = !{![[#CU1:]], ![[#CU2:]]}
 ;; Note that MD1 comes from the current module. MD2 is from the imported module. 
-;; We are checking if the imported MD2 doesn't end up having a null operand.
-; CHECK: !llvm.md = !{![[#MD1:]], ![[#MD2:]]}
+;; We are checking that MD2 is unified with MD1 and the imported MD2 doesn't
+;; end up having a null operand.
+; CHECK: !llvm.md = !{![[#MD1:]]}
 ; CHECK: ![[#MD3:]] = !{}
 ; CHECK: ![[#CU2]] = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: ![[#FILE2:]], isOptimized: false, runtimeVersion: 0, emissionKind: NoDebug)
-; CHECK: ![[#MD2]] = !{![[#MD3]]}
+; CHECK: ![[#MD1]] = !{![[#MD3]]}
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-scei-ps4"

Original file line number	Diff line number	Diff line change
`@@ -1133,8 +1133,11 @@ void IRLinker::linkNamedMDNodes() {`
`1133`	`1133`
`1134`	`1134`	`NamedMDNode *DestNMD = DstM.getOrInsertNamedMetadata(NMD.getName());`
`1135`	`1135`	`// Add Src elements into Dest node.`
`1136`		`- for (const MDNode *Op : NMD.operands())`
`1137`		`- DestNMD->addOperand(Mapper.mapMDNode(*Op));`
	`1136`	`+ for (const MDNode *Op : NMD.operands()) {`
	`1137`	`+ MDNode MD = Mapper.mapMDNode(Op);`
	`1138`	`+ if (!is_contained(DestNMD->operands(), MD))`
	`1139`	`+ DestNMD->addOperand(MD);`
	`1140`	`+ }`
`1138`	`1141`	`}`
`1139`	`1142`	`}`
`1140`	`1143`