[RISCV] implemented assembler pseudo floating point instructions

[niosHD]

Summary

Adds the assembler aliases for the floating point instructions
which can be mapped to a single canonical instruction. The missing
pseudo instructions (flw, fld, fsw, fsd) are marked as TODO. Other
things, like for example PCREL_LO, have to be implemented first.

This patch builds upon D40902.

[asb]

Thanks, this looks good. Checking this patch also unearthed a GNU binutils bug (lack of support for fsrmi and fsflagsi - filed https://sourceware.org/bugzilla/show_bug.cgi?id=22599).

[niosHD]

Great. I am going to work on the patch which enables aliases by default and updates the tests next. Is it preferred that only the RUN lines are updated to disable aliases in the already existing tests or should the actual content of the tests be updated with aliases?

[asb]

In D41071#953652, @niosHD wrote:

Great. I am going to work on the patch which enables aliases by default and updates the tests next. Is it preferred that only the RUN lines are updated to disable aliases in the already existing tests or should the actual content of the tests be updated with aliases?

I think keep the standard test/MC/RISCV/ tests (such as rv32i-valid.s) without aliases, but refresh the CodeGen tests (which should be trivial using update_llc_test_checks.py). The testing of the alias to allow rounding mode not to be explicitly specified should probably move to rvf-aliases-valid.s and rvd-aliases-valid.s

Thanks!

lib/Target/RISCV/RISCVInstrInfoD.td

def FCVT_D_LU : FPUnaryOp_r_frm<0b1101001, FPR64, GPR, "fcvt.d.lu"> {
   let rs2 = 0b00011;
 }
 def           : FPUnaryOpDynFrmAlias<FCVT_D_LU, "fcvt.d.lu", FPR64, GPR>;
 
 def FMV_D_X : FPUnaryOp_r<0b1111001, 0b000, FPR64, GPR, "fmv.d.x"> {
   let rs2 = 0b00000;
 }
 } // Predicates = [HasStdExtD, IsRV64]
+
+
+//===----------------------------------------------------------------------===//
+// Assembler Pseudo Instructions (User-Level ISA, Version 2.2, Chapter 20)
+//===----------------------------------------------------------------------===//
+let Predicates = [HasStdExtD] in {
+// TODO fld
+// TODO fsd
+
+def : InstAlias<"fmv.d $rd, $rs",  (FSGNJ_D  FPR64:$rd, FPR64:$rs, FPR64:$rs)>;
+def : InstAlias<"fabs.d $rd, $rs", (FSGNJX_D FPR64:$rd, FPR64:$rs, FPR64:$rs)>;
+def : InstAlias<"fneg.d $rd, $rs", (FSGNJN_D FPR64:$rd, FPR64:$rs, FPR64:$rs)>;
+} // Predicates = [HasStdExtD]

lib/Target/RISCV/RISCVInstrInfoF.td

 }
 def          : FPUnaryOpDynFrmAlias<FCVT_S_L, "fcvt.s.l", FPR32, GPR>;
 
 def FCVT_S_LU : FPUnaryOp_r_frm<0b1101000, FPR32, GPR, "fcvt.s.lu"> {
   let rs2 = 0b00011;
 }
 def           : FPUnaryOpDynFrmAlias<FCVT_S_LU, "fcvt.s.lu", FPR32, GPR>;
 } // Predicates = [HasStdExtF, IsRV64]
+
+//===----------------------------------------------------------------------===//
+// Assembler Pseudo Instructions (User-Level ISA, Version 2.2, Chapter 20)
+//===----------------------------------------------------------------------===//
+let Predicates = [HasStdExtF] in {
+// TODO flw
+// TODO fsw
+
+def : InstAlias<"fmv.s $rd, $rs",  (FSGNJ_S  FPR32:$rd, FPR32:$rs, FPR32:$rs)>;
+def : InstAlias<"fabs.s $rd, $rs", (FSGNJX_S FPR32:$rd, FPR32:$rs, FPR32:$rs)>;
+def : InstAlias<"fneg.s $rd, $rs", (FSGNJN_S FPR32:$rd, FPR32:$rs, FPR32:$rs)>;
+
+// The following csr instructions actually alias instructions from the base ISA.
+// However, it only makes sense to support them when the F extension is enabled.
+// CSR Addresses: 0x003 == fcsr, 0x002 == frm, 0x001 == fflags
+// NOTE: "frcsr", "frrm", and "frflags" are more specialized version of "csrr".
+def : InstAlias<"frcsr $rd",      (CSRRS GPR:$rd, 0x003, X0), 2>;
+def : InstAlias<"fscsr $rd, $rs", (CSRRW GPR:$rd, 0x003, GPR:$rs)>;
+def : InstAlias<"fscsr $rs",      (CSRRW      X0, 0x003, GPR:$rs), 2>;
+
+def : InstAlias<"frrm $rd",        (CSRRS  GPR:$rd, 0x002, X0), 2>;
+def : InstAlias<"fsrm $rd, $rs",   (CSRRW  GPR:$rd, 0x002, GPR:$rs)>;
+def : InstAlias<"fsrm $rs",        (CSRRW       X0, 0x002, GPR:$rs), 2>;
+def : InstAlias<"fsrmi $rd, $imm", (CSRRWI GPR:$rd, 0x002, uimm5:$imm)>;
+def : InstAlias<"fsrmi $imm",      (CSRRWI      X0, 0x002, uimm5:$imm), 2>;
+
+def : InstAlias<"frflags $rd",        (CSRRS  GPR:$rd, 0x001, X0), 2>;
+def : InstAlias<"fsflags $rd, $rs",   (CSRRW  GPR:$rd, 0x001, GPR:$rs)>;
+def : InstAlias<"fsflags $rs",        (CSRRW       X0, 0x001, GPR:$rs), 2>;
+def : InstAlias<"fsflagsi $rd, $imm", (CSRRWI GPR:$rd, 0x001, uimm5:$imm)>;
+def : InstAlias<"fsflagsi $imm",      (CSRRWI      X0, 0x001, uimm5:$imm), 2>;
+} // Predicates = [HasStdExtF]

test/MC/RISCV/rvd-aliases-valid.s

+# RUN: llvm-mc %s -triple=riscv32 -mattr=+d -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+d -riscv-no-aliases=false \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+d -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+d -riscv-no-aliases=false \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+d < %s \
+# RUN:     | llvm-objdump -d -mattr=+d -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+d < %s \
+# RUN:     | llvm-objdump -d -mattr=+d -riscv-no-aliases=false - \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+d < %s \
+# RUN:     | llvm-objdump -d -mattr=+d -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+d < %s \
+# RUN:     | llvm-objdump -d -mattr=+d -riscv-no-aliases=false - \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+
+# TODO fld
+# TODO fsd
+
+# CHECK-INST: fsgnj.d ft0, ft1, ft1
+# CHECK-ALIAS: fmv.d ft0, ft1
+fmv.d f0, f1
+# CHECK-INST: fsgnjx.d ft1, ft2, ft2
+# CHECK-ALIAS: fabs.d ft1, ft2
+fabs.d f1, f2
+# CHECK-INST: fsgnjn.d ft2, ft3, ft3
+# CHECK-ALIAS: fneg.d ft2, ft3
+fneg.d f2, f3

test/MC/RISCV/rvf-aliases-valid.s

+# RUN: llvm-mc %s -triple=riscv32 -mattr=+f -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv32 -mattr=+f -riscv-no-aliases=false \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+f -riscv-no-aliases \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc %s -triple=riscv64 -mattr=+f -riscv-no-aliases=false \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+f < %s \
+# RUN:     | llvm-objdump -d -mattr=+f -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv32 -mattr=+f < %s \
+# RUN:     | llvm-objdump -d -mattr=+f -riscv-no-aliases=false - \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+f < %s \
+# RUN:     | llvm-objdump -d -mattr=+f -riscv-no-aliases - \
+# RUN:     | FileCheck -check-prefix=CHECK-INST %s
+# RUN: llvm-mc -filetype=obj -triple riscv64 -mattr=+f < %s \
+# RUN:     | llvm-objdump -d -mattr=+f -riscv-no-aliases=false - \
+# RUN:     | FileCheck -check-prefix=CHECK-ALIAS %s
+
+# TODO flw
+# TODO fsw
+
+# CHECK-INST: fsgnj.s ft0, ft1, ft1
+# CHECK-ALIAS: fmv.s ft0, ft1
+fmv.s f0, f1
+# CHECK-INST: fsgnjx.s ft1, ft2, ft2
+# CHECK-ALIAS: fabs.s ft1, ft2
+fabs.s f1, f2
+# CHECK-INST: fsgnjn.s ft2, ft3, ft3
+# CHECK-ALIAS: fneg.s ft2, ft3
+fneg.s f2, f3
+
+# The following instructions actually alias instructions from the base ISA.
+# However, it only makes sense to support them when the F extension is enabled.
+# CHECK-INST: csrrs t0, 3, zero
+# CHECK-ALIAS: frcsr t0
+frcsr x5
+# CHECK-INST: csrrw t1, 3, t2
+# CHECK-ALIAS: fscsr t1, t2
+fscsr x6, x7
+# CHECK-INST: csrrw  zero, 3, t3
+# CHECK-ALIAS: fscsr t3
+fscsr x28
+
+# CHECK-INST: csrrs t4, 2, zero
+# CHECK-ALIAS: frrm t4
+frrm x29
+# CHECK-INST: csrrw  t5, 2, t4
+# CHECK-ALIAS: fsrm t5, t4
+fsrm x30, x29
+# CHECK-INST: csrrw  zero, 2, t6
+# CHECK-ALIAS: fsrm t6
+fsrm x31
+# CHECK-INST: csrrwi a0, 2, 31
+# CHECK-ALIAS: fsrmi a0, 31
+fsrmi x10, 0x1f
+# CHECK-INST: csrrwi  zero, 2, 30
+# CHECK-ALIAS: fsrmi 30
+fsrmi 0x1e
+
+# CHECK-INST: csrrs a1, 1, zero
+# CHECK-ALIAS: frflags a1
+frflags x11
+# CHECK-INST: csrrw a2, 1, a1
+# CHECK-ALIAS: fsflags a2, a1
+fsflags x12, x11
+# CHECK-INST: csrrw zero, 1, a3
+# CHECK-ALIAS: fsflags a3
+fsflags x13
+# CHECK-INST: csrrwi a4, 1, 29
+# CHECK-ALIAS: fsflagsi a4, 29
+fsflagsi x14, 0x1d
+# CHECK-INST: csrrwi zero, 1, 28
+# CHECK-ALIAS: fsflagsi 28
+fsflagsi 0x1c