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

Fixes 106412. The logic that skips the pass on already-lowered variables
doesn't cover the path that increases alignment of variables. If a
variable is allocated at 24 and then given 16 byte alignment, the
backend notices and fatal-errors on the inconsistency.

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
index 92b42e2..38f0b6d 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
@@ -1131,6 +1131,11 @@ private:
         continue;
       }
 
+      if (GV.isAbsoluteSymbolRef()) {
+        // If the variable is already allocated, don't change the alignment
+        continue;
+      }
+
       Align Alignment = AMDGPU::getAlign(DL, &GV);
       TypeSize GVSize = DL.getTypeAllocSize(GV.getValueType());