[Sparc] Use float register for integer constrained with "f" in inline asm

[dcederman]

Summary

Constraining an integer value to a floating point register using "f" causes an llvm_unreachable to trigger. This patch allows i32 integers to be placed in a single precision float register and i64 integers to be placed in a double precision float register. This matches the behavior of GCC.

For other types the llvm_unreachable is removed to instead trigger an error message that points out the offending line.

[jyknight]

Seems odd, but this appears to match GCC's behavior, so, LG.

lib/Target/Sparc/SparcISelLowering.cpp

SparcTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
   if (Constraint.size() == 1) {
     switch (Constraint[0]) {
     case 'r':
       if (VT == MVT::v2i32)
         return std::make_pair(0U, &SP::IntPairRegClass);
       else
         return std::make_pair(0U, &SP::IntRegsRegClass);
     case 'f':
-      if (VT == MVT::f32)
+      if (VT == MVT::f32 || VT == MVT::i32)
         return std::make_pair(0U, &SP::FPRegsRegClass);
-      else if (VT == MVT::f64)
+      else if (VT == MVT::f64 || VT == MVT::i64)
         return std::make_pair(0U, &SP::LowDFPRegsRegClass);
       else if (VT == MVT::f128)
         return std::make_pair(0U, &SP::LowQFPRegsRegClass);
-      llvm_unreachable("Unknown ValueType for f-register-type!");
-      break;
+      // This will generate an error message
+      return std::make_pair(0U, nullptr);
     case 'e':
-      if (VT == MVT::f32)
+      if (VT == MVT::f32 || VT == MVT::i32)
         return std::make_pair(0U, &SP::FPRegsRegClass);
-      else if (VT == MVT::f64)
+      else if (VT == MVT::f64 || VT == MVT::i64 )
         return std::make_pair(0U, &SP::DFPRegsRegClass);
       else if (VT == MVT::f128)
         return std::make_pair(0U, &SP::QFPRegsRegClass);
-      llvm_unreachable("Unknown ValueType for e-register-type!");
-      break;
+      // This will generate an error message
+      return std::make_pair(0U, nullptr);
     }
   } else if (!Constraint.empty() && Constraint.size() <= 5
               && Constraint[0] == '{' && *(Constraint.end()-1) == '}') {
     // constraint = '{r<d>}'
     // Remove the braces from around the name.
     StringRef name(Constraint.data()+1, Constraint.size()-2);
     // Handle register aliases:
     //       r0-r7   -> g0-g7

test/CodeGen/SPARC/inlineasm.ll

 ; CHECK: fadds %f20, %f20, %f20
 ; CHECK: faddd %f20, %f20, %f20
 define void @test_constraint_float_reg() {
 entry:
   tail call void asm sideeffect "fadds $0,$1,$2", "{f20},{f20},{f20}"(float 6.0, float 7.0, float 8.0)
   tail call void asm sideeffect "faddd $0,$1,$2", "{f20},{f20},{f20}"(double 9.0, double 10.0, double 11.0)
   ret void
 }
+
+; CHECK-LABEL: test_constraint_f_e_i32_i64:
+; CHECK: ld [%o0+%lo(.LCPI13_0)], %f0
+; CHECK: ldd [%o0+%lo(.LCPI13_1)], %f2
+; CHECK: fadds %f0, %f0, %f0
+; CHECK: faddd %f2, %f2, %f0
+
+define void @test_constraint_f_e_i32_i64() {
+entry:
+  %0 = call float asm sideeffect "fadds $1, $2, $0", "=f,f,e"(i32 0, i32 0)
+  %1 = call double asm sideeffect "faddd $1, $2, $0", "=f,f,e"(i64 0, i64 0)
+  ret void
+}