AMDGPU/GlobalISel: Fix readfirstlane pattern import

The imm folding optimization pattern failed to import. The instruction
pattern was already working, but failing to fail on SGPR inputs.

llvm/lib/Target/AMDGPU/SIInstructions.td

@@ -1938,7 +1938,7 @@ def : GCNPat<
 // the ignored src1.
 def : GCNPat<
   (int_amdgcn_readfirstlane (i32 imm:$src)),
-  (S_MOV_B32 $src)
+  (S_MOV_B32 SReg_32:$src)
 >;
 
 multiclass BFMPatterns <ValueType vt, InstSI BFM, InstSI MOV> {

llvm/lib/Target/AMDGPU/VOP1Instructions.td

@@ -156,7 +156,7 @@ def V_READFIRSTLANE_B32 :
   InstSI <(outs SReg_32:$vdst),
     (ins VRegOrLds_32:$src0),
     "v_readfirstlane_b32 $vdst, $src0",
-    [(set i32:$vdst, (int_amdgcn_readfirstlane i32:$src0))]>,
+    [(set i32:$vdst, (int_amdgcn_readfirstlane (i32 VRegOrLds_32:$src0)))]>,
   Enc32 {
 
   let isCodeGenOnly = 0;

llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-amdgcn.readfirstlane.mir

@@ -0,0 +1,63 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -march=amdgcn -mcpu=tahiti -run-pass=instruction-select -verify-machineinstrs -global-isel-abort=2 -pass-remarks-missed='gisel*' %s -o - 2> %t | FileCheck -check-prefix=GCN %s
+# RUN: FileCheck -check-prefix=ERR %s < %t
+
+# ERR: remark: <unknown>:0:0: cannot select: %1:sgpr(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.readfirstlane), %0:sgpr(s32) (in function: readfirstlane_s)
+
+---
+name: readfirstlane_v
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0
+    ; GCN-LABEL: name: readfirstlane_v
+    ; GCN: liveins: $vgpr0
+    ; GCN: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GCN: [[V_READFIRSTLANE_B32_:%[0-9]+]]:sreg_32 = V_READFIRSTLANE_B32 [[COPY]], implicit $exec
+    ; GCN: S_ENDPGM 0, implicit [[V_READFIRSTLANE_B32_]]
+    %0:vgpr(s32) = COPY $vgpr0
+    %1:sgpr(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.readfirstlane), %0
+    S_ENDPGM 0, implicit %1
+...
+
+---
+name: readfirstlane_v_imm
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+
+    ; GCN-LABEL: name: readfirstlane_v_imm
+    ; GCN: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 123, implicit $exec
+    ; GCN: [[COPY:%[0-9]+]]:sreg_32 = COPY [[V_MOV_B32_e32_]]
+    ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 [[COPY]]
+    ; GCN: S_ENDPGM 0, implicit [[S_MOV_B32_]]
+    %0:vgpr(s32) = G_CONSTANT i32 123
+    %1:sgpr(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.readfirstlane), %0
+    S_ENDPGM 0, implicit %1
+...
+
+# Make sure this fails to select
+---
+name: readfirstlane_s
+legalized: true
+regBankSelected: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $sgpr0
+    ; GCN-LABEL: name: readfirstlane_s
+    ; GCN: liveins: $sgpr0
+    ; GCN: [[COPY:%[0-9]+]]:sgpr(s32) = COPY $sgpr0
+    ; GCN: [[INT:%[0-9]+]]:sgpr(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.readfirstlane), [[COPY]](s32)
+    ; GCN: S_ENDPGM 0, implicit [[INT]](s32)
+    %0:sgpr(s32) = COPY $sgpr0
+    %1:sgpr(s32) = G_INTRINSIC intrinsic(@llvm.amdgcn.readfirstlane), %0
+    S_ENDPGM 0, implicit %1
+...