[llvm] [AMDGPU] Don't realign already allocated LDS. Point fix for 106412 (PR #106421)

[Jon Chesterfield via llvm-commits]

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@@ -0,0 +1,15 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+
+; Can't have a second variable without absolute_symbol showing it is realigned as
+; there is a fatal error on mixing absolute and non-absolute symbols
+
+; CHECK: @lds.dont_realign = internal addrspace(3) global i64 undef, align 2, !absolute_symbol !0
+ at lds.dont_realign = internal addrspace(3) global i64 undef, align 2, !absolute_symbol !0
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JonChesterfield wrote:

Why poison? Working model is that uses of uninitialised LDS are fine but meaningless, undef seems to capture that more accurately than poison

https://github.com/llvm/llvm-project/pull/106421