[ARM] Fix for MVE VPT block pass

[dmgreen]

Summary

We need to ensure that the number of T's is correct when adding multiple instructions into the same VPT block.

I have also moved the tests into Codegen/Thumb2/ to be with all the other MVE tests, in rL366655.

[SjoerdMeijer]

Thanks for fixing this.

llvm/lib/Target/ARM/Thumb2ITBlockPass.cpp

while (MBIter != EndIter) {
 
     if (Pred == ARMVCC::None) {
       ++MBIter;
       continue;
     }
 
     MachineInstrBuilder MIBuilder =
         BuildMI(Block, MBIter, dl, TII->get(ARM::MVE_VPST));
-    // The mask value for the VPST instruction is T = 0b1000 = 8
-    MIBuilder.addImm(VPTMaskValue::T);
 
     MachineBasicBlock::iterator VPSTInsertPos = MIBuilder.getInstr();
     int VPTInstCnt = 1;
     ARMVCC::VPTCodes NextPred;
 
     do {
       ++MBIter;
       NextPred = getVPTInstrPredicate(*MBIter, PredReg);
     } while (NextPred != ARMVCC::None && NextPred == Pred && ++VPTInstCnt < 4);
 
+    switch (VPTInstCnt) {
+    case 1:
+      MIBuilder.addImm(VPTMaskValue::T);
+      break;
+    case 2:
+      MIBuilder.addImm(VPTMaskValue::TT);
+      break;
+    case 3:
+      MIBuilder.addImm(VPTMaskValue::TTT);
+      break;
+    case 4:
+      MIBuilder.addImm(VPTMaskValue::TTTT);
+      break;
+    default:
+      llvm_unreachable("Unexpected number of instruction in a VPT block");
+    };
+
     MachineInstr *LastMI = &*MBIter;
     finalizeBundle(Block, VPSTInsertPos.getInstrIterator(),
                    ++LastMI->getIterator());
 
     Modified = true;
-    LLVM_DEBUG(dbgs() << "VPT block created for: "; MI->dump(););
+    LLVM_DEBUG(dbgs() << "VPT block created for: "; MI->dump());
 
     ++MBIter;
   }
   return Modified;
 }
 
 bool MVEVPTBlock::runOnMachineFunction(MachineFunction &Fn) {
   const ARMSubtarget &STI =

llvm/test/CodeGen/Thumb2/mve-vpt-block2.mir

frameInfo:
   restorePoint:    ''
 fixedStack:      []
 stack:           []
 constants:       []
 body:             |
   bb.0.entry:
     liveins: $q0, $q1, $q2, $q3, $r0
 
-    ; CHECK:       MVE_VPST 8, implicit-def $p0
+    ; CHECK:       MVE_VPST 4, implicit-def $p0
     ; CHECK-NEXT:  renamable $q0 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q1 = nnan ninf nsz MVE_VMINNMf32
 
     $vpr = VMSR_P0 killed $r0, 14, $noreg
     renamable $q0 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q2, renamable $q3, 1, renamable $vpr, killed renamable $q0
     renamable $q1 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q0, killed renamable $q3, 1, killed renamable $vpr, killed renamable $q1
     $q0 = MVE_VORR killed $q1, killed $q1, 0, $noreg, undef $q0
     tBX_RET 14, $noreg, implicit $q0
 
 ...

llvm/test/CodeGen/Thumb2/mve-vpt-block3.mir

frameInfo:
   restorePoint:    ''
 fixedStack:      []
 stack:           []
 constants:       []
 body:             |
   bb.0.entry:
     liveins: $q0, $q1, $q2, $q3, $r0
 
-    ; CHECK:       MVE_VPST 8, implicit-def $p0
+    ; CHECK:       MVE_VPST 1, implicit-def $p0
     ; CHECK-NEXT:  renamable $q2 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q2 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q0 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q1 = nnan ninf nsz MVE_VMINNMf32
 
     $vpr = VMSR_P0 killed $r0, 14, $noreg
     renamable $q2 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q2, renamable $q3, 1, renamable $vpr, undef renamable $q2
     renamable $q2 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q2, renamable $q2, 1, renamable $vpr, undef renamable $q2
     renamable $q0 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q2, renamable $q3, 1, renamable $vpr, killed renamable $q0
     renamable $q1 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q0, killed renamable $q3, 1, killed renamable $vpr, killed renamable $q1
     $q0 = MVE_VORR killed $q1, killed $q1, 0, $noreg, undef $q0
     tBX_RET 14, $noreg, implicit $q0
 
 ...

llvm/test/CodeGen/Thumb2/mve-vpt-block4.mir

frameInfo:
   restorePoint:    ''
 fixedStack:      []
 stack:           []
 constants:       []
 body:             |
   bb.0.entry:
     liveins: $q0, $q1, $q2, $q3, $r0
 
-    ; CHECK:       MVE_VPST 8, implicit-def $p0
+    ; CHECK:       MVE_VPST 1, implicit-def $p0
     ; CHECK-NEXT:  renamable $q2 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q2 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q0 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  renamable $q0 = nnan ninf nsz MVE_VMINNMf32
     ; CHECK-NEXT:  }
     ; CHECK-NEXT:  BUNDLE {{.*}} {
     ; CHECK-NEXT:    MVE_VPST 8, implicit-def $p0
     ; CHECK-NEXT:    renamable $q1 = nnan ninf nsz MVE_VMINNMf32

llvm/test/CodeGen/Thumb2/mve-vpt-block5.mir

 fixedStack:      []
 stack:           []
 constants:       []
 body:             |
   bb.0.entry:
     liveins: $q0, $q1, $q2, $r0
 
     ; CHECK:       BUNDLE {{.*}} {
-    ; CHECK-NEXT:    MVE_VPST 8, implicit-def $p0
+    ; CHECK-NEXT:    MVE_VPST 4, implicit-def $p0
     ; CHECK-NEXT:    renamable $q3 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q1, renamable $q2, 1, renamable $vpr, killed renamable $q3
     ; CHECK-NEXT:    renamable $q1 = nnan ninf nsz MVE_VMINNMf32 internal killed renamable $q3, internal renamable $q3, 1, renamable $vpr, undef renamable $q1
     ; CHECK-NEXT:    $q3 = MVE_VORR $q0, $q0, 0, $noreg, internal undef $q3
     ; CHECK-NEXT:  }
     ; CHECK-NEXT:  BUNDLE {{.*}} {
-    ; CHECK-NEXT:    MVE_VPST 8, implicit-def $p0
+    ; CHECK-NEXT:    MVE_VPST 4, implicit-def $p0
     ; CHECK-NEXT:    renamable $q3 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q1, renamable $q2, 1, renamable $vpr, killed renamable $q3
     ; CHECK-NEXT:    renamable $q0 = nnan ninf nsz MVE_VMINNMf32 internal killed renamable $q3, killed renamable $q2, 1, killed renamable $vpr, killed renamable $q0
     ; CHECK-NEXT:    tBX_RET 14, $noreg, implicit internal $q0
     ; CHECK-NEXT:  }
 
     $vpr = VMSR_P0 killed $r0, 14, $noreg
     $q3 = MVE_VORR $q0, $q0, 0, $noreg, undef $q3
     renamable $q3 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q1, renamable $q2, 1, renamable $vpr, killed renamable $q3
     renamable $q1 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q3, renamable $q3, 1, renamable $vpr, undef renamable $q1
     $q3 = MVE_VORR $q0, $q0, 0, $noreg, undef $q3
     renamable $q3 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q1, renamable $q2, 1, renamable $vpr, killed renamable $q3
     renamable $q0 = nnan ninf nsz MVE_VMINNMf32 killed renamable $q3, killed renamable $q2, 1, killed renamable $vpr, killed renamable $q0
     tBX_RET 14, $noreg, implicit $q0
 
 ...