[AArch64][GlobalISel] Widen G_FPTO*I before clamping

[paquette]

Summary

Going through our legalization rules and doing some cleanup.

Widening and then clamping is usually easier than clamping and then widening.

This allows us to legalize some weird types like s88.

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

AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
   getActionDefinitionsBuilder(G_FPEXT)
       .legalFor(
           {{s32, s16}, {s64, s16}, {s64, s32}, {v4s32, v4s16}, {v2s64, v2s32}})
       .clampMaxNumElements(0, s64, 2);
 
   // Conversions
   getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
       .legalForCartesianProduct({s32, s64, v2s64, v4s32, v2s32})
-      .clampScalar(0, s32, s64)
       .widenScalarToNextPow2(0)
-      .clampScalar(1, s32, s64)
-      .widenScalarToNextPow2(1);
+      .clampScalar(0, s32, s64)
+      .widenScalarToNextPow2(1)
+      .clampScalar(1, s32, s64);
 
   getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
       .legalForCartesianProduct({s32, s64, v2s64, v4s32, v2s32})
       .clampScalar(1, s32, s64)
       .minScalarSameAs(1, 0)
       .clampScalar(0, s32, s64)
       .widenScalarToNextPow2(0);
 

llvm/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir

bb.0:
     ; CHECK-LABEL: name: test_fptosi_s128_s32
     ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
     ; CHECK: [[FPTOSI:%[0-9]+]]:_(s128) = G_FPTOSI [[COPY]](s32)
     ; CHECK: $q0 = COPY [[FPTOSI]](s128)
     %0:_(s32) = COPY $w0
     %1:_(s128) = G_FPTOSI %0
     $q0 = COPY %1
 ...
+---
+name:            test_fptosi_s88_s88
+body: |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: test_fptosi_s88_s88
+    ; CHECK: [[DEF:%[0-9]+]]:_(s88) = G_IMPLICIT_DEF
+    ; CHECK: [[FPTOSI:%[0-9]+]]:_(s128) = G_FPTOSI [[DEF]](s88)
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s88) = G_TRUNC [[FPTOSI]](s128)
+    ; CHECK: %trunc:_(s64) = G_TRUNC [[TRUNC]](s88)
+    ; CHECK: $x0 = COPY %trunc(s64)
+    %0:_(s88) = G_IMPLICIT_DEF
+    %1:_(s88) = G_FPTOSI %0
+    %trunc:_(s64) = G_TRUNC %1
+    $x0 = COPY %trunc
+...
+---
+name:            test_fptosi_s88_s64
+body: |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: test_fptosi_s88_s64
+    ; CHECK: [[DEF:%[0-9]+]]:_(s64) = G_IMPLICIT_DEF
+    ; CHECK: [[FPTOSI:%[0-9]+]]:_(s128) = G_FPTOSI [[DEF]](s64)
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s88) = G_TRUNC [[FPTOSI]](s128)
+    ; CHECK: %trunc:_(s64) = G_TRUNC [[TRUNC]](s88)
+    ; CHECK: $x0 = COPY %trunc(s64)
+    %0:_(s64) = G_IMPLICIT_DEF
+    %1:_(s88) = G_FPTOSI %0
+    %trunc:_(s64) = G_TRUNC %1
+    $x0 = COPY %trunc
+...
+---
+name:            test_fptosi_s64_s88
+body: |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: test_fptosi_s64_s88
+    ; CHECK: [[DEF:%[0-9]+]]:_(s88) = G_IMPLICIT_DEF
+    ; CHECK: [[FPEXT:%[0-9]+]]:_(s128) = G_FPEXT [[DEF]](s88)
+    ; CHECK: [[FPTOSI:%[0-9]+]]:_(s64) = G_FPTOSI [[FPEXT]](s128)
+    ; CHECK: $x0 = COPY [[FPTOSI]](s64)
+    %0:_(s88) = G_IMPLICIT_DEF
+    %1:_(s64) = G_FPTOSI %0
+    $x0 = COPY %1