[RISCV] Add support for inline asm constraint vd (#111653)

It constrains vector registers excluding v0. Refer to
https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html RISC-V part.

This patch also adds a testcase for constraints vr, vd and vm.

Author: tclin914

clang/lib/Basic/Targets/RISCV.cpp

@@ -102,7 +102,7 @@ bool RISCVTargetInfo::validateAsmConstraint(
     return true;
   case 'v':
     // A vector register.
-    if (Name[1] == 'r' || Name[1] == 'm') {
+    if (Name[1] == 'r' || Name[1] == 'd' || Name[1] == 'm') {
       Info.setAllowsRegister();
       Name += 1;
       return true;

clang/test/CodeGen/RISCV/riscv-inline-asm-rvv.c

@@ -29,6 +29,14 @@ vint32m1_t test_vr(vint32m1_t a, vint32m1_t b) {
   return ret;
 }
 
+vint32m1_t test_vd(vint32m1_t a, vint32m1_t b) {
+// CHECK-LABEL: define{{.*}} @test_vd
+// CHECK: %0 = tail call <vscale x 2 x i32> asm sideeffect "vadd.vv $0, $1, $2", "=^vd,^vd,^vd"(<vscale x 2 x i32> %a, <vscale x 2 x i32> %b)
+  vint32m1_t ret;
+  asm volatile ("vadd.vv %0, %1, %2" : "=vd"(ret) : "vd"(a), "vd"(b));
+  return ret;
+}
+
 vbool1_t test_vm(vbool1_t a, vbool1_t b) {
 // CHECK-LABEL: define{{.*}} @test_vm
 // CHECK: %0 = tail call <vscale x 64 x i1> asm sideeffect "vmand.mm $0, $1, $2", "=^vm,^vm,^vm"(<vscale x 64 x i1> %a, <vscale x 64 x i1> %b)

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

@@ -20227,7 +20227,7 @@ RISCVTargetLowering::getConstraintType(StringRef Constraint) const {
       return C_Other;
     }
   } else {
-    if (Constraint == "vr" || Constraint == "vm")
+    if (Constraint == "vr" || Constraint == "vd" || Constraint == "vm")
       return C_RegisterClass;
   }
   return TargetLowering::getConstraintType(Constraint);
@@ -20275,6 +20275,19 @@ RISCVTargetLowering::getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
       if (TRI->isTypeLegalForClass(*RC, VT.SimpleTy))
         return std::make_pair(0U, RC);
     }
+  } else if (Constraint == "vd") {
+    for (const auto *RC :
+         {&RISCV::VRNoV0RegClass, &RISCV::VRM2NoV0RegClass,
+          &RISCV::VRM4NoV0RegClass, &RISCV::VRM8NoV0RegClass,
+          &RISCV::VRN2M1NoV0RegClass, &RISCV::VRN3M1NoV0RegClass,
+          &RISCV::VRN4M1NoV0RegClass, &RISCV::VRN5M1NoV0RegClass,
+          &RISCV::VRN6M1NoV0RegClass, &RISCV::VRN7M1NoV0RegClass,
+          &RISCV::VRN8M1NoV0RegClass, &RISCV::VRN2M2NoV0RegClass,
+          &RISCV::VRN3M2NoV0RegClass, &RISCV::VRN4M2NoV0RegClass,
+          &RISCV::VRN2M4NoV0RegClass}) {
+      if (TRI->isTypeLegalForClass(*RC, VT.SimpleTy))
+        return std::make_pair(0U, RC);
+    }
   } else if (Constraint == "vm") {
     if (TRI->isTypeLegalForClass(RISCV::VMV0RegClass, VT.SimpleTy))
       return std::make_pair(0U, &RISCV::VMV0RegClass);

llvm/test/CodeGen/RISCV/inline-asm-v-constraint.ll

@@ -0,0 +1,66 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+v -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV64I %s
+
+define <vscale x 1 x i8> @constraint_vr(<vscale x 1 x i8> %0, <vscale x 1 x i8> %1) nounwind {
+; RV32I-LABEL: constraint_vr:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    vadd.vv v8, v8, v9
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_vr:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    vadd.vv v8, v8, v9
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  %a = tail call <vscale x 1 x i8> asm "vadd.vv $0, $1, $2", "=^vr,^vr,^vr"(
+    <vscale x 1 x i8> %0, <vscale x 1 x i8> %1)
+  ret <vscale x 1 x i8> %a
+}
+
+define <vscale x 1 x i8> @constraint_vd(<vscale x 1 x i8> %0, <vscale x 1 x i8> %1) nounwind {
+; RV32I-LABEL: constraint_vd:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    vadd.vv v8, v8, v9
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_vd:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    vadd.vv v8, v8, v9
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  %a = tail call <vscale x 1 x i8> asm "vadd.vv $0, $1, $2", "=^vd,^vr,^vr"(
+    <vscale x 1 x i8> %0, <vscale x 1 x i8> %1)
+  ret <vscale x 1 x i8> %a
+}
+
+define <vscale x 1 x i1> @constraint_vm(<vscale x 1 x i1> %0, <vscale x 1 x i1> %1) nounwind {
+; RV32I-LABEL: constraint_vm:
+; RV32I:       # %bb.0:
+; RV32I-NEXT:    vmv1r.v v9, v0
+; RV32I-NEXT:    vmv1r.v v0, v8
+; RV32I-NEXT:    #APP
+; RV32I-NEXT:    vadd.vv v0, v9, v0
+; RV32I-NEXT:    #NO_APP
+; RV32I-NEXT:    ret
+;
+; RV64I-LABEL: constraint_vm:
+; RV64I:       # %bb.0:
+; RV64I-NEXT:    vmv1r.v v9, v0
+; RV64I-NEXT:    vmv1r.v v0, v8
+; RV64I-NEXT:    #APP
+; RV64I-NEXT:    vadd.vv v0, v9, v0
+; RV64I-NEXT:    #NO_APP
+; RV64I-NEXT:    ret
+  %a = tail call <vscale x 1 x i1> asm "vadd.vv $0, $1, $2", "=^vr,^vr,^vm"(
+    <vscale x 1 x i1> %0, <vscale x 1 x i1> %1)
+  ret <vscale x 1 x i1> %a
+}