[globalisel][tablegen] Enable the import of rules involving fma.

[dsanders]

Summary

G_FMA was recently added to GlobalISel which enables the import of rules
involving fma. Add the mapping to allow it.

[rovka]

Looks pretty trivial.

test/CodeGen/AArch64/GlobalISel/select-fma.mir

25

Nit: Extra register.

include/llvm/Target/GlobalISel/SelectionDAGCompat.td

 def : GINodeEquiv<G_FPEXT, fpextend>;
 def : GINodeEquiv<G_FPTRUNC, ftrunc>;
 def : GINodeEquiv<G_FPTOSI, fp_to_sint>;
 def : GINodeEquiv<G_FPTOUI, fp_to_uint>;
 def : GINodeEquiv<G_SITOFP, sint_to_fp>;
 def : GINodeEquiv<G_UITOFP, uint_to_fp>;
 def : GINodeEquiv<G_FADD, fadd>;
 def : GINodeEquiv<G_FSUB, fsub>;
+def : GINodeEquiv<G_FMA, fma>;
 def : GINodeEquiv<G_FMUL, fmul>;
 def : GINodeEquiv<G_FDIV, fdiv>;
 def : GINodeEquiv<G_FREM, frem>;
 def : GINodeEquiv<G_FPOW, fpow>;
 def : GINodeEquiv<G_FEXP2, fexp2>;
 def : GINodeEquiv<G_FLOG2, flog2>;
 def : GINodeEquiv<G_INTRINSIC, intrinsic_wo_chain>;
 def : GINodeEquiv<G_BR, br>;
 
 // Specifies the GlobalISel equivalents for SelectionDAG's ComplexPattern.
 // Should be used on defs that subclass GIComplexOperandMatcher<>.
 class GIComplexPatternEquiv<ComplexPattern seldag> {
   ComplexPattern SelDAGEquivalent = seldag;
 }

lib/Target/AArch64/AArch64LegalizerInfo.cpp

AArch64LegalizerInfo::AArch64LegalizerInfo() {
 
   for (unsigned Op : {G_UADDE, G_USUBE, G_SADDO, G_SSUBO, G_SMULH, G_UMULH}) {
     for (auto Ty : { s32, s64 })
       setAction({Op, Ty}, Legal);
 
     setAction({Op, 1, s1}, Legal);
   }
 
-  for (unsigned BinOp : {G_FADD, G_FSUB, G_FMUL, G_FDIV})
+  for (unsigned BinOp : {G_FADD, G_FSUB, G_FMA, G_FMUL, G_FDIV})
     for (auto Ty : {s32, s64})
       setAction({BinOp, Ty}, Legal);
 
   for (unsigned BinOp : {G_FREM, G_FPOW}) {
     setAction({BinOp, s32}, Libcall);
     setAction({BinOp, s64}, Libcall);
   }
 

test/CodeGen/AArch64/GlobalISel/select-fma.mir

+# RUN: llc -O0 -mtriple=aarch64-- -run-pass=instruction-select -verify-machineinstrs -global-isel %s -o - | FileCheck %s
+
+--- |
+  target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+
+  define void @FMADDSrrr_fpr() { ret void }
+...
+
+---
+# CHECK-LABEL: name: FMADDSrrr_fpr
+name:            FMADDSrrr_fpr
+legalized:       true
+regBankSelected: true
+
+# CHECK:      registers:
+# CHECK-NEXT:  - { id: 0, class: fpr32, preferred-register: '' }
+# CHECK-NEXT:  - { id: 1, class: fpr32, preferred-register: '' }
+# CHECK-NEXT:  - { id: 2, class: fpr32, preferred-register: '' }
+# CHECK-NEXT:  - { id: 3, class: fpr32, preferred-register: '' }
+registers:
+  - { id: 0, class: fpr }
+  - { id: 1, class: fpr }
+  - { id: 2, class: fpr }
+  - { id: 3, class: fpr }
+  - { id: 4, class: fpr }
+
+# CHECK:  body:
+# CHECK:    %0 = COPY %w0
+# CHECK:    %1 = COPY %w1
+# CHECK:    %2 = COPY %w2
+# CHECK:    %3 = FMADDSrrr %0, %1, %2
+body:             |
+  bb.0:
+    liveins: %w0, %w1, %w2
+
+    %0(s32) = COPY %w0
+    %1(s32) = COPY %w1
+    %2(s32) = COPY %w2
+    %3(s32) = G_FMA %0, %1, %2
+    %x0 = COPY %3
+...
+