[AArch64][GlobalISel] Expand handling for fptosi and fptoui (#70635)

Now that we have more types handled for zext/sext and trunc, it is
possible to get more types working for the vector float to integer
conversions. This patch adds fp16, widening and narrowing vector support
to handle more types. The smaller types wil be expanded to the size of
the larger element type. A couple of case require more awkward truncates
to get working as they go from illegal to illegal types.

Author: davemgreen

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -5124,7 +5124,9 @@ LegalizerHelper::moreElementsVector(MachineInstr &MI, unsigned TypeIdx,
   }
   case TargetOpcode::G_TRUNC:
   case TargetOpcode::G_FPTRUNC:
-  case TargetOpcode::G_FPEXT: {
+  case TargetOpcode::G_FPEXT:
+  case TargetOpcode::G_FPTOSI:
+  case TargetOpcode::G_FPTOUI: {
     if (TypeIdx != 0)
       return UnableToLegalize;
     Observer.changingInstr(MI);

llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp

@@ -643,10 +643,33 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
   // Conversions
   getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
       .legalForCartesianProduct({s32, s64, v2s64, v4s32, v2s32})
+      .legalIf([=](const LegalityQuery &Query) {
+        return HasFP16 &&
+               (Query.Types[1] == s16 || Query.Types[1] == v4s16 ||
+                Query.Types[1] == v8s16) &&
+               (Query.Types[0] == s32 || Query.Types[0] == s64 ||
+                Query.Types[0] == v4s16 || Query.Types[0] == v8s16);
+      })
       .widenScalarToNextPow2(0)
       .clampScalar(0, s32, s64)
       .widenScalarToNextPow2(1)
-      .clampScalar(1, s32, s64);
+      .clampScalarOrElt(1, MinFPScalar, s64)
+      .moreElementsToNextPow2(0)
+      .widenScalarIf(
+          [=](const LegalityQuery &Query) {
+            return Query.Types[0].getScalarSizeInBits() >
+                   Query.Types[1].getScalarSizeInBits();
+          },
+          LegalizeMutations::changeElementSizeTo(1, 0))
+      .widenScalarIf(
+          [=](const LegalityQuery &Query) {
+            return Query.Types[0].getScalarSizeInBits() <
+                   Query.Types[1].getScalarSizeInBits();
+          },
+          LegalizeMutations::changeElementSizeTo(0, 1))
+      .clampNumElements(0, v4s16, v8s16)
+      .clampNumElements(0, v2s32, v4s32)
+      .clampMaxNumElements(0, s64, 2);
 
   getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
       .legalForCartesianProduct({s32, s64, v2s64, v4s32, v2s32})

llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir

@@ -503,12 +503,12 @@
 # DEBUG-NEXT: .. the first uncovered type index: 2, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
 # DEBUG-NEXT: G_FPTOSI (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
-# DEBUG-NEXT: .. the first uncovered type index: 2, OK
-# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
+# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: G_FPTOUI (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
-# DEBUG-NEXT: .. the first uncovered type index: 2, OK
-# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
+# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: G_SITOFP (opcode {{[0-9]+}}): 2 type indices, 0 imm indices
 # DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
 # DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected