[GlobalISel] Remove semantic operand of G_IS_FPCLASS

Instruction G_IS_FPCLASS had an operand that represented floating-point
semantics of its first operand. It allowed types that have the same length,
like `bfloat16` and `half`, to be distinguished. Unfortunately, it is
not sufficient, as other operation still cannot distinguish such types.
Solution of this problem must be more general, so now this operand is removed.

Differential Revision: https://reviews.llvm.org/D138004

Author: spavloff

llvm/docs/GlobalISel/GenericOpcode.rst

@@ -484,8 +484,7 @@ G_IS_FPCLASS
 ^^^^^^^^^^^^
 
 Tests if the first operand, which must be floating-point scalar or vector, has
-floating-point class specified by the second operand. The third operand
-specifies floating-point semantics of the tested value. Returns non-zero (true)
+floating-point class specified by the second operand. Returns non-zero (true)
 or zero (false). It's target specific whether a true value is 1, ~0U, or some
 other non-zero value. If the first operand is a vector, the returned value is a
 vector of the same length.

llvm/include/llvm/Target/GenericOpcodes.td

@@ -748,7 +748,7 @@ def G_FCANONICALIZE : GenericInstruction {
 // Generic opcode equivalent to the llvm.is_fpclass intrinsic.
 def G_IS_FPCLASS: GenericInstruction {
   let OutOperandList = (outs type0:$dst);
-  let InOperandList = (ins type1:$src, unknown:$test, unknown:$fpsem);
+  let InOperandList = (ins type1:$src, unknown:$test);
   let hasSideEffects = false;
 }
 

llvm/lib/CodeGen/MachineVerifier.cpp

@@ -1714,16 +1714,6 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
       report("Incorrect floating-point class set (operand 2)", MI);
       break;
     }
-    const MachineOperand &SemanticsMO = MI->getOperand(3);
-    if (!SemanticsMO.isImm()) {
-      report("floating-point semantics (operand 3) must be an immediate", MI);
-      break;
-    }
-    int64_t Semantics = SemanticsMO.getImm();
-    if (Semantics < 0 || Semantics > APFloat::S_MaxSemantics) {
-      report("Incorrect floating-point semantics (operand 3)", MI);
-      break;
-    }
     break;
   }
   case TargetOpcode::G_ASSERT_ALIGN: {

llvm/test/MachineVerifier/test_g_is_fpclass.mir

@@ -15,26 +15,23 @@ body:             |
     %ptr:_(p0) = COPY $x0
     %vector:_(<4 x s32>) = COPY $q0
 
-    %val1:_(s1) = G_IS_FPCLASS %s32, 1
+    %val1:_(s1) = G_IS_FPCLASS %s32
     ; CHECK: *** Bad machine code: Too few operands ***
-    ; CHECK: 4 operands expected, but 3 given.
+    ; CHECK: 3 operands expected, but 2 given.
 
-    %val2:_(p0) = G_IS_FPCLASS %s32, 3, 2
+    %val2:_(p0) = G_IS_FPCLASS %s32, 3
     ; CHECK: *** Bad machine code: Destination must be a scalar or vector of scalars ***
 
-    %val3:_(s1) = G_IS_FPCLASS %s32, 1, 66
-    ; CHECK: *** Bad machine code: Incorrect floating-point semantics (operand 3) ***
-
-    %val4:_(s1) = G_IS_FPCLASS %s32, 7777, 2
+    %val4:_(s1) = G_IS_FPCLASS %s32, 7777
     ; CHECK: *** Bad machine code: Incorrect floating-point class set (operand 2) ***
 
-    %val5:_(s1) = G_IS_FPCLASS %ptr:_(p0), 3, 2
+    %val5:_(s1) = G_IS_FPCLASS %ptr:_(p0), 3
     ; CHECK: *** Bad machine code: Source must be a scalar or vector of scalars ***
 
-    %var6:_(s1) = G_IS_FPCLASS %vector:_(<4 x s32>), 1, 2
+    %var6:_(s1) = G_IS_FPCLASS %vector:_(<4 x s32>), 1
     ; CHECK: *** Bad machine code: operand types must be all-vector or all-scalar ***
 
-    %var7:_(<2 x s1>) = G_IS_FPCLASS %vector:_(<4 x s32>), 1, 2
+    %var7:_(<2 x s1>) = G_IS_FPCLASS %vector:_(<4 x s32>), 1
     ; CHECK: *** Bad machine code: operand types must preserve number of vector elements ***
 
 ...