[RISCV] Add additional CSR instruction aliases (imm. operands)

This patch adds CSR instructions aliases for the cases where the instruction 
takes an immediate operand but the alias doesn't have the i suffix. This is 
necessary for gas/gcc compatibility.

gas doesn't do a similar conversion for fsflags or fsrm, so this should be 
complete.

Differential Revision: https://reviews.llvm.org/D55008
Patch by Luís Marques.

llvm-svn: 347991

2 files changed, 30 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
index 90f8c97bf64..9dbf8c6d88f 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -580,6 +580,16 @@ def : InstAlias<"csrwi $csr, $imm", (CSRRWI X0, csr_sysreg:$csr, uimm5:$imm)>;
 def : InstAlias<"csrsi $csr, $imm", (CSRRSI X0, csr_sysreg:$csr, uimm5:$imm)>;
 def : InstAlias<"csrci $csr, $imm", (CSRRCI X0, csr_sysreg:$csr, uimm5:$imm)>;
 
+let EmitPriority = 0 in {
+def : InstAlias<"csrw $csr, $imm", (CSRRWI X0, csr_sysreg:$csr, uimm5:$imm)>;
+def : InstAlias<"csrs $csr, $imm", (CSRRSI X0, csr_sysreg:$csr, uimm5:$imm)>;
+def : InstAlias<"csrc $csr, $imm", (CSRRCI X0, csr_sysreg:$csr, uimm5:$imm)>;
+
+def : InstAlias<"csrrw $rd, $csr, $imm", (CSRRWI GPR:$rd, csr_sysreg:$csr, uimm5:$imm)>;
+def : InstAlias<"csrrs $rd, $csr, $imm", (CSRRSI GPR:$rd, csr_sysreg:$csr, uimm5:$imm)>;
+def : InstAlias<"csrrc $rd, $csr, $imm", (CSRRCI GPR:$rd, csr_sysreg:$csr, uimm5:$imm)>;
+}
+
 def : InstAlias<"sfence.vma",     (SFENCE_VMA      X0, X0)>;
 def : InstAlias<"sfence.vma $rs", (SFENCE_VMA GPR:$rs, X0)>;
 
diff --git a/llvm/test/MC/RISCV/rvi-aliases-valid.s b/llvm/test/MC/RISCV/rvi-aliases-valid.s
index 4acabe216a1..a4aef05f8be 100644
--- a/llvm/test/MC/RISCV/rvi-aliases-valid.s
+++ b/llvm/test/MC/RISCV/rvi-aliases-valid.s
@@ -181,6 +181,26 @@ csrsi 0xfff, 0x10
 # CHECK-S-OBJ: csrci sscratch, 17
 csrci 0x140, 0x11
 
+# CHECK-S-OBJ-NOALIAS: csrrwi zero, 336, 7
+# CHECK-S-OBJ: csrwi 336, 7
+csrw 0x150, 7
+# CHECK-S-OBJ-NOALIAS: csrrsi zero, 336, 7
+# CHECK-S-OBJ: csrsi 336, 7
+csrs 0x150, 7
+# CHECK-S-OBJ-NOALIAS: csrrci zero, 336, 7
+# CHECK-S-OBJ: csrci 336, 7
+csrc 0x150, 7
+
+# CHECK-S-OBJ-NOALIAS: csrrwi t0, 336, 15
+# CHECK-S-OBJ: csrrwi t0, 336, 15
+csrrw t0, 0x150, 0xf
+# CHECK-S-OBJ-NOALIAS: csrrsi t0, 4095, 16
+# CHECK-S-OBJ: csrrsi t0, 4095, 16
+csrrs t0, 0xfff, 0x10
+# CHECK-S-OBJ-NOALIAS: csrrci t0, sscratch, 17
+# CHECK-S-OBJ: csrrci t0, sscratch, 17
+csrrc t0, 0x140, 0x11
+
 # CHECK-S-OBJ-NOALIAS: sfence.vma zero, zero
 # CHECK-S-OBJ: sfence.vma
 sfence.vma