[llvm] [AMDGPU] Emit the relocation symbol for LDS and named barrier when object linking is enabled (PR #192380)

[Matt Arsenault via llvm-commits]

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+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -amdgpu-enable-object-linking < %s | FileCheck -check-prefixes=ASM %s
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -amdgpu-enable-object-linking -filetype=obj < %s | llvm-readobj -r --syms - | FileCheck -check-prefixes=ELF %s
+
+; Test that with object linking enabled, external LDS declarations produce
+; @abs32 at lo relocations, SHN_AMDGPU_LDS symbols, and .amdgpu_lds directives.
+; Covers multiple LDS variables with different sizes and alignments (including
+; zero-sized dynamic LDS), usage from both kernels and device functions, and
+; group_segment_fixed_size = 0 (linker patches via binary patching).
+
+ at lds_large = external addrspace(3) global [256 x i8], align 16
+ at lds_small = external addrspace(3) global [128 x i8], align 4
+ at lds_dynamic = external addrspace(3) global [0 x i8], align 8
+
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arsenm wrote:

Can you test some of the degenerate global object cases, like a function in addrspace(3), and an alias 

https://github.com/llvm/llvm-project/pull/192380