[AMDGPU] Add sext_trunc in RegBankCombiner (#131623)

Author: Pierre-vh

llvm/lib/Target/AMDGPU/AMDGPUCombine.td

@@ -182,5 +182,5 @@ def AMDGPURegBankCombiner : GICombiner<
    zext_trunc_fold, int_minmax_to_med3, ptr_add_immed_chain,
    fp_minmax_to_clamp, fp_minmax_to_med3, fmed3_intrinsic_to_clamp,
    identity_combines, redundant_and, constant_fold_cast_op,
-   cast_of_cast_combines]> {
+   cast_of_cast_combines, sext_trunc]> {
 }

llvm/test/CodeGen/AMDGPU/GlobalISel/combine-trunc-sext.mir

@@ -1,5 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
-# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=tahiti -run-pass=amdgpu-prelegalizer-combiner -verify-machineinstrs %s -o - | FileCheck -check-prefix=GCN %s
+# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=tahiti -run-pass=amdgpu-prelegalizer-combiner %s -o - | FileCheck -check-prefixes=GCN,PRELEGAL %s
+# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=tahiti -run-pass=amdgpu-regbank-combiner %s -o - | FileCheck -check-prefixes=GCN,RBCOMB %s
 
 ---
 name: trunc_sext_i32_i16
@@ -65,12 +66,20 @@ body:             |
   bb.0:
     liveins: $vgpr0_vgpr1_vgpr2_vgpr3
 
-    ; GCN-LABEL: name: trunc_sext_v4i32_v4i16
-    ; GCN: liveins: $vgpr0_vgpr1_vgpr2_vgpr3
-    ; GCN-NEXT: {{  $}}
-    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
-    ; GCN-NEXT: [[SEXT_INREG:%[0-9]+]]:_(<4 x s32>) = G_SEXT_INREG [[COPY]], 16
-    ; GCN-NEXT: $vgpr0_vgpr1_vgpr2_vgpr3 = COPY [[SEXT_INREG]](<4 x s32>)
+    ; PRELEGAL-LABEL: name: trunc_sext_v4i32_v4i16
+    ; PRELEGAL: liveins: $vgpr0_vgpr1_vgpr2_vgpr3
+    ; PRELEGAL-NEXT: {{  $}}
+    ; PRELEGAL-NEXT: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    ; PRELEGAL-NEXT: [[SEXT_INREG:%[0-9]+]]:_(<4 x s32>) = G_SEXT_INREG [[COPY]], 16
+    ; PRELEGAL-NEXT: $vgpr0_vgpr1_vgpr2_vgpr3 = COPY [[SEXT_INREG]](<4 x s32>)
+    ;
+    ; RBCOMB-LABEL: name: trunc_sext_v4i32_v4i16
+    ; RBCOMB: liveins: $vgpr0_vgpr1_vgpr2_vgpr3
+    ; RBCOMB-NEXT: {{  $}}
+    ; RBCOMB-NEXT: [[COPY:%[0-9]+]]:_(<4 x s32>) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    ; RBCOMB-NEXT: [[TRUNC:%[0-9]+]]:_(<4 x s16>) = G_TRUNC [[COPY]](<4 x s32>)
+    ; RBCOMB-NEXT: [[SEXT:%[0-9]+]]:_(<4 x s32>) = G_SEXT [[TRUNC]](<4 x s16>)
+    ; RBCOMB-NEXT: $vgpr0_vgpr1_vgpr2_vgpr3 = COPY [[SEXT]](<4 x s32>)
     %0:_(<4 x s32>) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
     %1:_(<4 x s16>) = G_TRUNC %0
     %2:_(<4 x s32>) = G_SEXT %1
@@ -84,12 +93,20 @@ body:             |
   bb.0:
     liveins: $vgpr0_vgpr1
 
-    ; GCN-LABEL: name: trunc_sext_v4i16_v4i8
-    ; GCN: liveins: $vgpr0_vgpr1
-    ; GCN-NEXT: {{  $}}
-    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(<4 x s16>) = COPY $vgpr0_vgpr1
-    ; GCN-NEXT: [[SEXT_INREG:%[0-9]+]]:_(<4 x s16>) = G_SEXT_INREG [[COPY]], 8
-    ; GCN-NEXT: $vgpr0_vgpr1 = COPY [[SEXT_INREG]](<4 x s16>)
+    ; PRELEGAL-LABEL: name: trunc_sext_v4i16_v4i8
+    ; PRELEGAL: liveins: $vgpr0_vgpr1
+    ; PRELEGAL-NEXT: {{  $}}
+    ; PRELEGAL-NEXT: [[COPY:%[0-9]+]]:_(<4 x s16>) = COPY $vgpr0_vgpr1
+    ; PRELEGAL-NEXT: [[SEXT_INREG:%[0-9]+]]:_(<4 x s16>) = G_SEXT_INREG [[COPY]], 8
+    ; PRELEGAL-NEXT: $vgpr0_vgpr1 = COPY [[SEXT_INREG]](<4 x s16>)
+    ;
+    ; RBCOMB-LABEL: name: trunc_sext_v4i16_v4i8
+    ; RBCOMB: liveins: $vgpr0_vgpr1
+    ; RBCOMB-NEXT: {{  $}}
+    ; RBCOMB-NEXT: [[COPY:%[0-9]+]]:_(<4 x s16>) = COPY $vgpr0_vgpr1
+    ; RBCOMB-NEXT: [[TRUNC:%[0-9]+]]:_(<4 x s8>) = G_TRUNC [[COPY]](<4 x s16>)
+    ; RBCOMB-NEXT: [[SEXT:%[0-9]+]]:_(<4 x s16>) = G_SEXT [[TRUNC]](<4 x s8>)
+    ; RBCOMB-NEXT: $vgpr0_vgpr1 = COPY [[SEXT]](<4 x s16>)
     %0:_(<4 x s16>) = COPY $vgpr0_vgpr1
     %1:_(<4 x s8>) = G_TRUNC %0
     %2:_(<4 x s16>) = G_SEXT %1