AMDGPU/GlobalISel: Mark G_BITCAST s32 <--> <2 x s16> legal

[arsenm]

LGTM

test/CodeGen/AMDGPU/GlobalISel/legalize-bitcast.mir

8 ↗

(On Diff #102277)

Probably should include types in the test name

[tstellar]

I was planning to put all the bitcasts in the same function. I think this is easier to do with mir tests.

[arsenm]

Ok that makes sense

llvm/trunk/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp

 #ifndef LLVM_BUILD_GLOBAL_ISEL
 #error "You shouldn't build this"
 #endif
 
 AMDGPULegalizerInfo::AMDGPULegalizerInfo() {
   using namespace TargetOpcode;
 
   const LLT S1= LLT::scalar(1);
+  const LLT V2S16 = LLT::vector(2, 16);
   const LLT S32 = LLT::scalar(32);
   const LLT S64 = LLT::scalar(64);
   const LLT P1 = LLT::pointer(1, 64);
   const LLT P2 = LLT::pointer(2, 64);
 
   setAction({G_ADD, S32}, Legal);
 
+  setAction({G_BITCAST, V2S16}, Legal);
+  setAction({G_BITCAST, 1, S32}, Legal);
+
+  setAction({G_BITCAST, S32}, Legal);
+  setAction({G_BITCAST, 1, V2S16}, Legal);
+
   // FIXME: i1 operands to intrinsics should always be legal, but other i1
   // values may not be legal.  We need to figure out how to distinguish
   // between these two scenarios.
   setAction({G_CONSTANT, S1}, Legal);
   setAction({G_CONSTANT, S32}, Legal);
   setAction({G_CONSTANT, S64}, Legal);
 
   setAction({G_FCONSTANT, S32}, Legal);

llvm/trunk/test/CodeGen/AMDGPU/GlobalISel/legalize-bitcast.mir

+# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=fiji -run-pass=legalizer -global-isel %s -o - | FileCheck %s
+
+--- |
+  define void @test_bitcast() { ret void }
+...
+
+---
+name:            test_bitcast
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body: |
+  bb.0:
+    liveins: %vgpr0
+    ; CHECK-LABEL: name: test_bitcast
+    ; CHECK: %1(<2 x s16>) = G_BITCAST %0
+    ; CHECK: %2(s32) = G_BITCAST %1
+
+    %0(s32) = COPY %vgpr0
+    %1(<2 x s16>) = G_BITCAST %0
+    %2(s32) = G_BITCAST %1
+...