[llvm] [GlobalISel] Combine (sext (trunc x)) to (sext_inreg x) (PR #131622)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,117 @@
+# 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
+
+---
+name: trunc_sext_i32_i16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0
+
+    ; GCN-LABEL: name: trunc_sext_i32_i16
+    ; GCN: liveins: $vgpr0
+    ; GCN-NEXT: {{  $}}
+    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; GCN-NEXT: [[SEXT_INREG:%[0-9]+]]:_(s32) = G_SEXT_INREG [[COPY]], 16
+    ; GCN-NEXT: $vgpr0 = COPY [[SEXT_INREG]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s16) = G_TRUNC %0
+    %2:_(s32) = G_SEXT %1
+    $vgpr0 = COPY %2
+...
+
+---
+name: trunc_sext_i32_i8
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0
+
+    ; GCN-LABEL: name: trunc_sext_i32_i8
+    ; GCN: liveins: $vgpr0
+    ; GCN-NEXT: {{  $}}
+    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; GCN-NEXT: [[SEXT_INREG:%[0-9]+]]:_(s32) = G_SEXT_INREG [[COPY]], 8
+    ; GCN-NEXT: $vgpr0 = COPY [[SEXT_INREG]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s8) = G_TRUNC %0
+    %2:_(s32) = G_SEXT %1
+    $vgpr0 = COPY %2
+...
+
+---
+name: trunc_sext_i64_i32
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+
+    ; GCN-LABEL: name: trunc_sext_i64_i32
+    ; GCN: liveins: $vgpr0_vgpr1
+    ; GCN-NEXT: {{  $}}
+    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; GCN-NEXT: [[SEXT_INREG:%[0-9]+]]:_(s64) = G_SEXT_INREG [[COPY]], 32
+    ; GCN-NEXT: $vgpr0_vgpr1 = COPY [[SEXT_INREG]](s64)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s32) = G_TRUNC %0
+    %2:_(s64) = G_SEXT %1
+    $vgpr0_vgpr1 = COPY %2
+...
+
+---
+name: trunc_sext_v4i32_v4i16
+tracksRegLiveness: true
+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>)
+    %0:_(<4 x s32>) = COPY $vgpr0_vgpr1_vgpr2_vgpr3
+    %1:_(<4 x s16>) = G_TRUNC %0
+    %2:_(<4 x s32>) = G_SEXT %1
+    $vgpr0_vgpr1_vgpr2_vgpr3 = COPY %2
+...
+
+---
+name: trunc_sext_v4i16_v4i8
+tracksRegLiveness: true
+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>)
+    %0:_(<4 x s16>) = COPY $vgpr0_vgpr1
+    %1:_(<4 x s8>) = G_TRUNC %0
+    %2:_(<4 x s16>) = G_SEXT %1
+    $vgpr0_vgpr1 = COPY %2
+...
+
+---
+name: trunc_sext_mismatching_types
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+
+    ; GCN-LABEL: name: trunc_sext_mismatching_types
+    ; GCN: liveins: $vgpr0_vgpr1
+    ; GCN-NEXT: {{  $}}
+    ; GCN-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; GCN-NEXT: [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s64)
+    ; GCN-NEXT: [[SEXT:%[0-9]+]]:_(s32) = G_SEXT [[TRUNC]](s16)
+    ; GCN-NEXT: $vgpr0 = COPY [[SEXT]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s16) = G_TRUNC %0
+    %2:_(s32) = G_SEXT %1
+    $vgpr0 = COPY %2
+...
----------------
arsenm wrote:

Missing nsw cases? If there's an existing test for the NSW cases, they should be merged 

https://github.com/llvm/llvm-project/pull/131622