Automerge: [AArch64][GlobalISel] Add better basic legalization for llround. (#168427)

This adds handling for f16 and f128 lround/llround under LP64 targets,
promoting the f16 where needed and using a libcall for f128. This
codegen is now identical to the selection dag version.

Author: davemgreen

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -3439,6 +3439,18 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     Observer.changedInstr(MI);
     return Legalized;
   }
+  case TargetOpcode::G_LROUND:
+  case TargetOpcode::G_LLROUND:
+    Observer.changingInstr(MI);
+
+    if (TypeIdx == 0)
+      widenScalarDst(MI, WideTy);
+    else
+      widenScalarSrc(MI, WideTy, 1, TargetOpcode::G_FPEXT);
+
+    Observer.changedInstr(MI);
+    return Legalized;
+
   case TargetOpcode::G_INTTOPTR:
     if (TypeIdx != 1)
       return UnableToLegalize;

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

@@ -449,10 +449,12 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
       .minScalar(0, s32)
       .libcallFor({{s32, s32}, {s64, s32}, {s128, s32}});
 
-  // TODO: Libcall support for s128.
-  // TODO: s16 should be legal with full FP16 support.
   getActionDefinitionsBuilder({G_LROUND, G_LLROUND})
-      .legalFor({{s64, s32}, {s64, s64}});
+      .legalFor({{s64, s32}, {s64, s64}})
+      .legalFor(HasFP16, {{s64, s16}})
+      .minScalar(0, s64)
+      .minScalar(1, s32)
+      .libcallFor({{s64, s128}});
 
   // TODO: Custom legalization for mismatched types.
   getActionDefinitionsBuilder(G_FCOPYSIGN)

llvm/test/CodeGen/AArch64/llround-conv-fp16.ll

@@ -1,12 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
 ; RUN: llc < %s -mtriple=aarch64 | FileCheck %s --check-prefixes=CHECK-NOFP16
 ; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 | FileCheck %s --check-prefixes=CHECK-FP16
-; RUN: llc < %s -mtriple=aarch64 -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK-NOFP16,CHECK-GI
-; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK-FP16,CHECK-GI
-
-; CHECK-GI:       warning: Instruction selection used fallback path for testmhhs
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmhws
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmhxs
+; RUN: llc < %s -mtriple=aarch64 -global-isel | FileCheck %s --check-prefixes=CHECK-NOFP16
+; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 -global-isel | FileCheck %s --check-prefixes=CHECK-FP16
 
 define i16 @testmhhs(half %x) {
 ; CHECK-NOFP16-LABEL: testmhhs:

llvm/test/CodeGen/AArch64/llround-conv.ll

@@ -1,9 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
 ; RUN: llc < %s -mtriple=aarch64 -mattr=+neon | FileCheck %s
-; RUN: llc < %s -mtriple=aarch64 -mattr=+neon -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-GI
-
-; CHECK-GI:       warning: Instruction selection used fallback path for testmswl
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmsll
+; RUN: llc < %s -mtriple=aarch64 -mattr=+neon -global-isel | FileCheck %s
 
 define i32 @testmsws(float %x) {
 ; CHECK-LABEL: testmsws:

llvm/test/CodeGen/AArch64/lround-conv-fp16.ll

@@ -1,12 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
 ; RUN: llc < %s -mtriple=aarch64 | FileCheck %s --check-prefixes=CHECK-NOFP16
 ; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 | FileCheck %s --check-prefixes=CHECK-FP16
-; RUN: llc < %s -mtriple=aarch64 -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK-NOFP16,CHECK-GI
-; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK-FP16,CHECK-GI
-
-; CHECK-GI:       warning: Instruction selection used fallback path for testmhhs
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmhws
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmhxs
+; RUN: llc < %s -mtriple=aarch64 -global-isel | FileCheck %s --check-prefixes=CHECK-NOFP16
+; RUN: llc < %s -mtriple=aarch64 -mattr=+fullfp16 -global-isel | FileCheck %s --check-prefixes=CHECK-FP16
 
 define i16 @testmhhs(half %x) {
 ; CHECK-NOFP16-LABEL: testmhhs:

llvm/test/CodeGen/AArch64/lround-conv.ll

@@ -1,9 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
 ; RUN: llc < %s -mtriple=aarch64 -mattr=+neon | FileCheck %s
-; RUN: llc < %s -mtriple=aarch64 -mattr=+neon -global-isel -global-isel-abort=2 2>&1 | FileCheck %s --check-prefixes=CHECK,CHECK-GI
-
-; CHECK-GI:       warning: Instruction selection used fallback path for testmswl
-; CHECK-GI-NEXT:  warning: Instruction selection used fallback path for testmsll
+; RUN: llc < %s -mtriple=aarch64 -mattr=+neon -global-isel | FileCheck %s
 
 define i32 @testmsws(float %x) {
 ; CHECK-LABEL: testmsws: