[llvm] [SelectionDAG] Salvage debuginfo when combining load and z|s ext instrs. (PR #188544)

[Orlando Cazalet-Hyams via llvm-commits]

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@@ -0,0 +1,61 @@
+; This test checks that after SelectionDAG runs, it preserves the debug info that is lost due to the DAGCombiner combining a load and a sext instruction, where the #dbg_value is pointing to the result of the load.
+; RUN: llc %s -mtriple=x86_64-unkown-linux -start-before=x86-isel -stop-after=x86-isel -o - | FileCheck %s --check-prefix=MIR
+; RUN: llc -O2 %s -start-before=x86-isel -mtriple=x86_64-unkown-linux --filetype=obj -o %t.o 
+; RUN: llvm-dwarfdump %t.o --name Idx | FileCheck %s --check-prefix=DUMP
+; RUN: llvm-dwarfdump %t.o --name Idx2 | FileCheck %s --check-prefix=DUMP2
+
+; MIR: ![[IDX:[0-9]+]] = !DILocalVariable(name: "Idx"
+; MIR: ![[IDX2:[0-9]+]] = !DILocalVariable(name: "Idx2"
+; MIR-LABEL: bb.0
+; MIR: %{{[0-9a-f]+}}{{.*}} = MOVSX64rm32 ${{.*}}, 1, $noreg, @GlobArr, $noreg, debug-instr-number [[INSTR_NUM:[0-9]+]]
+; MIR-NEXT: DBG_INSTR_REF ![[IDX]], !DIExpression(DW_OP_LLVM_arg, 0,  DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_LLVM_convert, 64, DW_ATE_signed, DW_OP_stack_value), dbg-instr-ref([[INSTR_NUM]], 0)
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OCHyams wrote:

ping

https://github.com/llvm/llvm-project/pull/188544