GlobalISel: Relax verifier between physreg and typed vreg (llvm#159281)

Accept mismatched register size and type size if the type is legal
for the register class.

For AMDGPU boolean registers have 2 possible interpretations depending
on the use context type. e.g., these are both equally valid:

  %0:_(s1) = COPY $vcc
  %1:_(s64) = COPY $vcc

vcc is a 64-bit register, which can be interpreted as a 1-bit or 64-bit
value depending on the use context. SelectionDAG has never required
exact
match between the register size and the used value type. You can assign
a type with a smaller size to a larger register class. Relax the
verifier
to match.  There are several hacks holding together these copies in
various places, and this is preparation to remove one of them.

The x86 test change is from what I would consider an X86 usage bug. X86
defines an FR32 register class and F16 register class, but the F16
register
class is functionally an alias of F32 with the same members and size.
There's
no need to have the F16 class.

Author: arsenm

llvm/lib/CodeGen/MachineVerifier.cpp

@@ -2376,20 +2376,24 @@ void MachineVerifier::visitMachineInstrBefore(const MachineInstr *MI) {
 
     // If we have only one valid type, this is likely a copy between a virtual
     // and physical register.
-    TypeSize SrcSize = TRI->getRegSizeInBits(SrcReg, *MRI);
-    TypeSize DstSize = TRI->getRegSizeInBits(DstReg, *MRI);
+    TypeSize SrcSize = TypeSize::getZero();
+    TypeSize DstSize = TypeSize::getZero();
     if (SrcReg.isPhysical() && DstTy.isValid()) {
       const TargetRegisterClass *SrcRC =
           TRI->getMinimalPhysRegClassLLT(SrcReg, DstTy);
-      if (SrcRC)
-        SrcSize = TRI->getRegSizeInBits(*SrcRC);
+      if (!SrcRC)
+        SrcSize = TRI->getRegSizeInBits(SrcReg, *MRI);
+    } else {
+      SrcSize = TRI->getRegSizeInBits(SrcReg, *MRI);
     }
 
     if (DstReg.isPhysical() && SrcTy.isValid()) {
       const TargetRegisterClass *DstRC =
           TRI->getMinimalPhysRegClassLLT(DstReg, SrcTy);
-      if (DstRC)
-        DstSize = TRI->getRegSizeInBits(*DstRC);
+      if (!DstRC)
+        DstSize = TRI->getRegSizeInBits(DstReg, *MRI);
+    } else {
+      DstSize = TRI->getRegSizeInBits(DstReg, *MRI);
     }
 
     // The next two checks allow COPY between physical and virtual registers,

llvm/test/MachineVerifier/AMDGPU/test_copy_physregs_llt_virtreg.mir

@@ -0,0 +1,58 @@
+# RUN: not --crash llc -mtriple=amdgcn -run-pass=none -filetype=null %s 2>&1 | FileCheck -implicit-check-not="Bad machine code" %s
+
+---
+name:            test_valid_copies
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0, $vcc
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s16) = COPY $vgpr0
+    %2:_(s64) = COPY $vcc
+    %3:_(s1) = COPY $vcc
+    $vgpr0 = COPY %0
+    $vgpr0 = COPY %0
+    $vcc = COPY %2
+    $vcc = COPY %3
+...
+
+---
+name:            test_invalid_copies
+tracksRegLiveness: true
+body:             |
+  bb.0:
+  liveins: $vgpr0_vgpr1, $vgpr2, $vcc
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: %0:_(s32) = COPY $vgpr0_vgpr1
+  %0:_(s32) = COPY $vgpr0_vgpr1
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: %1:_(s64) = COPY $vgpr2
+  %1:_(s64) = COPY $vgpr2
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: %2:_(s32) = COPY $vcc
+  %2:_(s32) = COPY $vcc
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: %3:_(s8) = COPY $vgpr2
+  %3:_(s8) = COPY $vgpr2
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: $vgpr0_vgpr1 = COPY %0:_(s32)
+  $vgpr0_vgpr1 = COPY %0
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: $vgpr2 = COPY %1:_(s64)
+  $vgpr2 = COPY %1
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: $vcc = COPY %2:_(s32)
+  $vcc = COPY %2
+
+  ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
+  ; CHECK: - instruction: $vgpr2 = COPY %3:_(s8)
+  $vgpr2 = COPY %3
+
+...

llvm/test/MachineVerifier/test_copy_physregs_x86.mir

@@ -29,34 +29,26 @@ body:             |
     liveins: $xmm0, $xmm1, $xmm2, $xmm3
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: %0:_(s16) = COPY $xmm0
-    %0:_(s16) = COPY $xmm0
+    ; CHECK: - instruction: %0:_(<4 x s16>) = COPY $xmm1
+    %0:_(<4 x s16>) = COPY $xmm1
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: %1:_(<4 x s16>) = COPY $xmm1
-    %1:_(<4 x s16>) = COPY $xmm1
+    ; CHECK: - instruction: %1:_(s256) = COPY $xmm2
+    %1:_(s256) = COPY $xmm2
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: %2:_(s256) = COPY $xmm2
-    %2:_(s256) = COPY $xmm2
+    ; CHECK: - instruction: %2:_(<8 x s32>) = COPY $xmm3
+    %2:_(<8 x s32>) = COPY $xmm3
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: %3:_(<8 x s32>) = COPY $xmm3
-    %3:_(<8 x s32>) = COPY $xmm3
+    ; CHECK: - instruction: $xmm1 = COPY %0:_(<4 x s16>)
+    $xmm1 = COPY %0
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: $xmm0 = COPY %0:_(s16)
-    $xmm0 = COPY %0
-
-    ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: $xmm1 = COPY %1:_(<4 x s16>)
-    $xmm1 = COPY %1
+    ; CHECK: - instruction: $xmm2 = COPY %1:_(s256)
+    $xmm2 = COPY %1
 
     ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: $xmm2 = COPY %2:_(s256)
-    $xmm2 = COPY %2
-
-    ; CHECK: *** Bad machine code: Copy Instruction is illegal with mismatching sizes ***
-    ; CHECK: - instruction: $xmm3 = COPY %3:_(<8 x s32>)
-    $xmm3 = COPY %3
+    ; CHECK: - instruction: $xmm3 = COPY %2:_(<8 x s32>)
+    $xmm3 = COPY %2
 ...