[ARM][GlobalISel] Support for G_ANYEXT

G_ANYEXT can be introduced by the legalizer when widening scalars. Add
support for it in the register bank info (same mapping as everything
else) and in the instruction selector.

When selecting it, we treat it as a COPY, just like G_TRUNC. On this
occasion we get rid of some assertions in selectCopy so we can reuse it.
This shouldn't be a problem at the moment since we're not supporting any
complicated cases (e.g. FPR, different register banks). We might want to
separate the paths when we do.

llvm-svn: 302778

llvm/lib/Target/ARM/ARMInstructionSelector.cpp

@@ -101,14 +101,6 @@ static bool selectCopy(MachineInstr &I, const TargetInstrInfo &TII,
   assert(RegBank && "Can't get reg bank for virtual register");
 
   const unsigned DstSize = MRI.getType(DstReg).getSizeInBits();
-  (void)DstSize;
-  unsigned SrcReg = I.getOperand(1).getReg();
-  const unsigned SrcSize = RBI.getSizeInBits(SrcReg, MRI, TRI);
-  (void)SrcSize;
-  // We use copies for trunc, so it's ok for the size of the destination to be
-  // smaller (the higher bits will just be undefined).
-  assert(DstSize <= SrcSize && "Copy with different width?!");
-
   assert((RegBank->getID() == ARM::GPRRegBankID ||
           RegBank->getID() == ARM::FPRRegBankID) &&
          "Unsupported reg bank");
@@ -330,6 +322,7 @@ bool ARMInstructionSelector::select(MachineInstr &I) const {
     }
     break;
   }
+  case G_ANYEXT:
   case G_TRUNC: {
     // The high bits are undefined, so there's nothing special to do, just
     // treat it as a copy.
@@ -340,12 +333,12 @@ bool ARMInstructionSelector::select(MachineInstr &I) const {
     const auto &DstRegBank = *RBI.getRegBank(DstReg, MRI, TRI);
 
     if (SrcRegBank.getID() != DstRegBank.getID()) {
-      DEBUG(dbgs() << "G_TRUNC operands on different register banks\n");
+      DEBUG(dbgs() << "G_TRUNC/G_ANYEXT operands on different register banks\n");
       return false;
     }
 
     if (SrcRegBank.getID() != ARM::GPRRegBankID) {
-      DEBUG(dbgs() << "G_TRUNC on non-GPR not supported yet\n");
+      DEBUG(dbgs() << "G_TRUNC/G_ANYEXT on non-GPR not supported yet\n");
       return false;
     }
 

llvm/lib/Target/ARM/ARMRegisterBankInfo.cpp

@@ -225,6 +225,7 @@ ARMRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
   case G_UDIV:
   case G_SEXT:
   case G_ZEXT:
+  case G_ANYEXT:
   case G_TRUNC:
   case G_GEP:
     // FIXME: We're abusing the fact that everything lives in a GPR for now; in

llvm/test/CodeGen/ARM/GlobalISel/arm-instruction-select.mir

@@ -4,6 +4,8 @@
   define void @test_sext_s1() { ret void }
   define void @test_sext_s8() { ret void }
   define void @test_zext_s16() { ret void }
+  define void @test_anyext_s8() { ret void }
+  define void @test_anyext_s16() { ret void }
 
   define void @test_trunc_s32_16() { ret void }
 
@@ -149,6 +151,58 @@ body:             |
     ; CHECK: BX_RET 14, _, implicit %r0
 ...
 ---
+name:            test_anyext_s8
+# CHECK-LABEL: name: test_anyext_s8
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+body:             |
+  bb.0:
+    liveins: %r0
+
+    %0(s8) = COPY %r0
+    ; CHECK: [[VREGX:%[0-9]+]] = COPY %r0
+
+    %1(s32) = G_ANYEXT %0(s8)
+    ; CHECK: [[VREGEXT:%[0-9]+]] = COPY [[VREGX]]
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[VREGEXT]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
+---
+name:            test_anyext_s16
+# CHECK-LABEL: name: test_anyext_s16
+legalized:       true
+regBankSelected: true
+selected:        false
+# CHECK: selected: true
+registers:
+  - { id: 0, class: gprb }
+  - { id: 1, class: gprb }
+body:             |
+  bb.0:
+    liveins: %r0
+
+    %0(s16) = COPY %r0
+    ; CHECK: [[VREGX:%[0-9]+]] = COPY %r0
+
+    %1(s32) = G_ANYEXT %0(s16)
+    ; CHECK: [[VREGEXT:%[0-9]+]] = COPY [[VREGX]]
+
+    %r0 = COPY %1(s32)
+    ; CHECK: %r0 = COPY [[VREGEXT]]
+
+    BX_RET 14, _, implicit %r0
+    ; CHECK: BX_RET 14, _, implicit %r0
+...
+---
 name:            test_trunc_s32_16
 # CHECK-LABEL: name: test_trunc_s32_16
 legalized:       true

llvm/test/CodeGen/ARM/GlobalISel/arm-regbankselect.mir

@@ -25,6 +25,9 @@
 
   define void @test_constants() { ret void }
 
+  define void @test_anyext_s8_32() { ret void }
+  define void @test_anyext_s16_32() { ret void }
+
   define void @test_trunc_s32_16() { ret void }
 
   define void @test_fadd_s32() #0 { ret void }
@@ -500,6 +503,48 @@ body:             |
     BX_RET 14, _, implicit %r0
 ...
 ---
+name:            test_anyext_s8_32
+# CHECK-LABEL: name: test_anyext_s8_32
+legalized:       true
+regBankSelected: false
+selected:        false
+# CHECK: registers:
+# CHECK: - { id: 0, class: gprb }
+# CHECK: - { id: 1, class: gprb }
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+body:             |
+  bb.0:
+    liveins: %r0
+
+    %0(s8) = COPY %r0
+    %1(s32) = G_ANYEXT %0(s8)
+    %r0 = COPY %1(s32)
+    BX_RET 14, _, implicit %r0
+...
+---
+name:            test_anyext_s16_32
+# CHECK-LABEL: name: test_anyext_s16_32
+legalized:       true
+regBankSelected: false
+selected:        false
+# CHECK: registers:
+# CHECK: - { id: 0, class: gprb }
+# CHECK: - { id: 1, class: gprb }
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+body:             |
+  bb.0:
+    liveins: %r0
+
+    %0(s16) = COPY %r0
+    %1(s32) = G_ANYEXT %0(s16)
+    %r0 = COPY %1(s32)
+    BX_RET 14, _, implicit %r0
+...
+---
 name:            test_trunc_s32_16
 # CHECK-LABEL: name: test_trunc_s32_16
 legalized:       true