[llvm] [RegAlloc] Account for use availability when applying rematerializable weight discount (PR #159180)

[Matt Arsenault via llvm-commits]

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@@ -91,15 +91,17 @@ body:             |
   bb.0:
     ; GCN-LABEL: name: test_no_remat_s_mov_b32_vreg_src_short_lr
     ; GCN: renamable $sgpr0 = IMPLICIT_DEF
-    ; GCN-NEXT: renamable $sgpr1 = S_MOV_B32 renamable $sgpr0
-    ; GCN-NEXT: SI_SPILL_S32_SAVE killed renamable $sgpr1, %stack.1, implicit $exec, implicit $sgpr32 :: (store (s32) into %stack.1, addrspace 5)
-    ; GCN-NEXT: renamable $sgpr1 = S_MOV_B32 renamable $sgpr0
-    ; GCN-NEXT: SI_SPILL_S32_SAVE killed renamable $sgpr1, %stack.0, implicit $exec, implicit $sgpr32 :: (store (s32) into %stack.0, addrspace 5)
+    ; GCN-NEXT: renamable $sgpr1 = S_MOV_B32 killed renamable $sgpr0
+    ; GCN-NEXT: renamable $sgpr0 = IMPLICIT_DEF
     ; GCN-NEXT: renamable $sgpr0 = S_MOV_B32 killed renamable $sgpr0
-    ; GCN-NEXT: renamable $sgpr1 = SI_SPILL_S32_RESTORE %stack.1, implicit $exec, implicit $sgpr32 :: (load (s32) from %stack.1, addrspace 5)
-    ; GCN-NEXT: S_NOP 0, implicit killed renamable $sgpr1
-    ; GCN-NEXT: renamable $sgpr1 = SI_SPILL_S32_RESTORE %stack.0, implicit $exec, implicit $sgpr32 :: (load (s32) from %stack.0, addrspace 5)
+    ; GCN-NEXT: SI_SPILL_S32_SAVE killed renamable $sgpr0, %stack.1, implicit $exec, implicit $sgpr32 :: (store (s32) into %stack.1, addrspace 5)
+    ; GCN-NEXT: renamable $sgpr0 = IMPLICIT_DEF
----------------
arsenm wrote:

I suppose this grew by one IMPLICIT_DEF 

https://github.com/llvm/llvm-project/pull/159180