GlobalISel: Verify G_EXTRACT

[paquette]

LGTM

[arsenm]

r353759

lib/CodeGen/MachineVerifier.cpp

case TargetOpcode::G_FCMP: {
     LLT SrcTy = MRI->getType(MI->getOperand(2).getReg());
 
     if ((DstTy.isVector() != SrcTy.isVector()) ||
         (DstTy.isVector() && DstTy.getNumElements() != SrcTy.getNumElements()))
       report("Generic vector icmp/fcmp must preserve number of lanes", MI);
 
     break;
   }
+  case TargetOpcode::G_EXTRACT: {
+    const MachineOperand &SrcOp = MI->getOperand(1);
+    if (!SrcOp.isReg()) {
+      report("extract source must be a register", MI);
+      break;
+    }
+
+    const MachineOperand &OffsetOp = MI->getOperand(2);
+    if (!OffsetOp.isImm()) {
+      report("extract offset must be a constant", MI);
+      break;
+    }
+
+    unsigned DstSize = MRI->getType(MI->getOperand(0).getReg()).getSizeInBits();
+    unsigned SrcSize = MRI->getType(SrcOp.getReg()).getSizeInBits();
+    if (SrcSize == DstSize)
+      report("extract source must be larger than result", MI);
+
+    if (DstSize + OffsetOp.getImm() > SrcSize)
+      report("extract reads past end of register", MI);
+    break;
+  }
   default:
     break;
   }
 }
 
 void MachineVerifier::visitMachineInstrBefore(const MachineInstr *MI) {
   const MCInstrDesc &MCID = MI->getDesc();
   if (MI->getNumOperands() < MCID.getNumOperands()) {

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

 ---
 name: extract_s8_v5s1_offset4
 legalized: true
 
 body: |
   bb.0:
     ; CHECK-LABEL: name: extract_s8_v5s1_offset4
     ; CHECK: [[DEF:%[0-9]+]]:_(<5 x s16>) = G_IMPLICIT_DEF
-    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s16) = G_EXTRACT [[DEF]](<5 x s16>), 80
+    ; CHECK: [[EXTRACT:%[0-9]+]]:_(s16) = G_EXTRACT [[DEF]](<5 x s16>), 64
     ; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[EXTRACT]](s16)
     ; CHECK: $vgpr0 = COPY [[ANYEXT]](s32)
     %0:_(<5 x s1>) = G_IMPLICIT_DEF
-    %1:_(s1) = G_EXTRACT %0, 5
+    %1:_(s1) = G_EXTRACT %0, 4
     %2:_(s32) = G_ANYEXT %1
     $vgpr0 = COPY %2
 ...
 
 ---
 name: extract_v2s16_v4s16_offset32
 legalized: true
 

test/Verifier/test_g_extract.mir

+# RUN: not llc -march=aarch64 -o /dev/null -run-pass=none -verify-machineinstrs %s 2>&1 | FileCheck %s
+# REQUIRES: global-isel, aarch64-registered-target
+
+---
+name:            test_extract
+legalized:       true
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+liveins:
+body:             |
+  bb.0:
+
+    ; CHECK: Bad machine code: Too few operands
+    %0:_(s32) = G_EXTRACT
+
+    ; CHECK: Bad machine code: Too few operands
+    %1:_(s32) = G_EXTRACT 0
+
+    ; CHECK: Bad machine code: extract source must be a register
+    %2:_(s32) = G_EXTRACT 0, 1
+
+    ; CHECK: Bad machine code: extract offset must be a constant
+    %3:_(s32) = G_IMPLICIT_DEF
+    %4:_(s32) = G_CONSTANT i32 0
+    %5:_(s16) = G_EXTRACT %3, %4
+
+    ; CHECK: Bad machine code: extract source must be larger than result
+    %6:_(s32) = G_IMPLICIT_DEF
+    %7:_(s32) = G_EXTRACT %6, 0
+
+    ; CHECK: Bad machine code: extract reads past end of register
+    %8:_(s1) = G_EXTRACT %6, 32
+
+...