[llvm] [RISCV][GISEL] Select G_IMPLICIT_DEF (PR #73060)

[Craig Topper via llvm-commits]

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@@ -0,0 +1,59 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv32 -mattr=+f -run-pass=instruction-select -simplify-mir -verify-machineinstrs %s -o - \
+# RUN: | FileCheck -check-prefix=RV32F %s
+
+---
+name:            implicit_def_gpr
+legalized:       true
+regBankSelected: true
+body:             |
+  bb.0:
+    ; RV32F-LABEL: name: implicit_def_gpr
+    ; RV32F: [[DEF:%[0-9]+]]:gpr = IMPLICIT_DEF
+    ; RV32F-NEXT: [[ADD:%[0-9]+]]:gpr = ADD [[DEF]], [[DEF]]
+    ; RV32F-NEXT: $x10 = COPY [[ADD]]
+    %0:gprb(s32) = G_IMPLICIT_DEF
+    %1:gprb(s32) = G_ADD %0, %0
+    $x10 = COPY %1(s32)
+...
+---
+name:            implicit_def_copy_gpr
+legalized:       true
+regBankSelected: true
+body:             |
+  bb.0:
+    ; RV32F-LABEL: name: implicit_def_copy_gpr
+    ; RV32F: [[DEF:%[0-9]+]]:gpr = IMPLICIT_DEF
+    ; RV32F-NEXT: $x10 = COPY [[DEF]]
+    %0:gprb(s32) = G_IMPLICIT_DEF
+    %1:gprb(s32) = COPY %0(s32)
+    $x10 = COPY %1(s32)
+...
+
+---
+name:            implicit_def_fpr
+legalized:       true
+regBankSelected: true
+body:             |
+  bb.0:
+    ; RV32F-LABEL: name: implicit_def_fpr
+    ; RV32F: [[DEF:%[0-9]+]]:fpr32 = IMPLICIT_DEF
+    ; RV32F-NEXT: [[FADD_S:%[0-9]+]]:fpr32 = nofpexcept FADD_S [[DEF]], [[DEF]], 7
+    ; RV32F-NEXT: $f10_f = COPY [[FADD_S]]
+    %0:fprb(s32) = G_IMPLICIT_DEF
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topperc wrote:

Can register bank selection produce this? There's no code for G_IMPLICIT_DEF in RISCVRegistrBankInfo so it would always have gprb?

https://github.com/llvm/llvm-project/pull/73060