[X86] Skip debug instructions in tile copy lowering#209640
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nikic merged 1 commit intoJul 15, 2026
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@llvm/pr-subscribers-backend-x86 Author: Krisitan Erik Olsen (Kristianerik) ChangesX86LowerTileCopy iterates over instructions in reverse to track live registers, calling LiveRegUnits::stepBackward on every instruction unconditionally. Since commit 16b2ef3 added an assertion that stepBackward must not receive debug instructions, functions containing debug info hit the assertion during tile copy lowering. 2 Files Affected:
diff --git a/llvm/lib/Target/X86/X86LowerTileCopy.cpp b/llvm/lib/Target/X86/X86LowerTileCopy.cpp
index e5a374dfcc0b6..628f691279600 100644
--- a/llvm/lib/Target/X86/X86LowerTileCopy.cpp
+++ b/llvm/lib/Target/X86/X86LowerTileCopy.cpp
@@ -87,6 +87,8 @@ static bool lowerTileCopy(MachineFunction &MF) {
LiveRegUnits UsedRegs(*TRI);
UsedRegs.addLiveOuts(MBB);
for (MachineInstr &MI : llvm::make_early_inc_range(reverse(MBB))) {
+ if (MI.isDebugInstr())
+ continue;
UsedRegs.stepBackward(MI);
if (!MI.isCopy())
continue;
diff --git a/llvm/test/CodeGen/X86/AMX/amx-lower-tile-copy-debuginfo.ll b/llvm/test/CodeGen/X86/AMX/amx-lower-tile-copy-debuginfo.ll
new file mode 100644
index 0000000000000..975aa5c1e5f6c
--- /dev/null
+++ b/llvm/test/CodeGen/X86/AMX/amx-lower-tile-copy-debuginfo.ll
@@ -0,0 +1,28 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+amx-int8 -mattr=+avx512f -verify-machineinstrs -o /dev/null
+
+define void @test_debug_instr(ptr %arg) #0 !dbg !4 {
+ #dbg_declare(ptr %arg, !12, !DIExpression(), !15)
+ %1 = call x86_amx @llvm.x86.cast.vector.to.tile.v1024i8(<1024 x i8> zeroinitializer)
+ %2 = call x86_amx @llvm.x86.tdpbssd.internal(i16 0, i16 0, i16 0, x86_amx %1, x86_amx %1, x86_amx %1)
+ ret void
+}
+
+declare x86_amx @llvm.x86.cast.vector.to.tile.v1024i8(<1024 x i8>) #1
+declare x86_amx @llvm.x86.tdpbssd.internal(i16, i16, i16, x86_amx, x86_amx, x86_amx) #2
+
+attributes #0 = { "target-features"="+amx-int8" }
+attributes #1 = { nocallback nofree nosync nounwind willreturn memory(none) }
+attributes #2 = { nounwind }
+
+!llvm.module.flags = !{!0}
+!llvm.dbg.cu = !{!1}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DICompileUnit(language: DW_LANG_C11, file: !2, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, nameTableKind: None)
+!2 = !DIFile(filename: "test.c", directory: "/tmp")
+!3 = !{}
+!4 = distinct !DISubprogram(name: "test_debug_instr", linkageName: "test_debug_instr", scope: !2, file: !2, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !3)
+!9 = distinct !DISubroutineType(types: !3)
+!12 = distinct !DILocalVariable(name: "a", arg: 1, scope: !4, file: !2, line: 1, type: !13)
+!13 = !DICompositeType(tag: DW_TAG_structure_type, name: "__tile1024i", scope: !4, file: !2, size: 16384, align: 8192, flags: DIFlagPublic, elements: !3, identifier: "__tile1024i")
+!15 = !DILocation(line: 1, column: 1, scope: !4)
|
phoebewang
reviewed
Jul 15, 2026
| @@ -0,0 +1,28 @@ | |||
| ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+amx-int8 -mattr=+avx512f -verify-machineinstrs -o /dev/null | |||
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X86LowerTileCopy iterates over instructions in reverse to track live registers, calling LiveRegUnits::stepBackward on every instruction unconditionally. Since commit 16b2ef3 added an assertion that stepBackward must not receive debug instructions, functions containing debug info hit the assertion during tile copy lowering. This patch skips debug instructions early in the loop, matching the guard pattern used in RegisterScavenging.cpp and X86FixupBWInsts.cpp. Fixes llvm#209512 (cherry picked from commit 3e4160f)
pedroMVicente
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Jul 15, 2026
X86LowerTileCopy iterates over instructions in reverse to track live registers, calling LiveRegUnits::stepBackward on every instruction unconditionally. Since commit 16b2ef3 added an assertion that stepBackward must not receive debug instructions, functions containing debug info hit the assertion during tile copy lowering. This patch skips debug instructions early in the loop, matching the guard pattern used in RegisterScavenging.cpp and X86FixupBWInsts.cpp. Fixes llvm#209512
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X86LowerTileCopy iterates over instructions in reverse to track live registers, calling LiveRegUnits::stepBackward on every instruction unconditionally. Since commit 16b2ef3 added an assertion that stepBackward must not receive debug instructions, functions containing debug info hit the assertion during tile copy lowering.
This patch skips debug instructions early in the loop, matching the guard pattern used in RegisterScavenging.cpp and X86FixupBWInsts.cpp.
Fixes #209512