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| author | Joel Sing <joel@sing.id.au> | 2020-01-29 20:14:18 +1100 |
|---|---|---|
| committer | Joel Sing <joel@sing.id.au> | 2020-01-29 16:35:37 +0000 |
| commit | a50c3ffbd47e3dcfc1b5bd2a2d19d55731481eaa (patch) | |
| tree | a6b487eada71261849e490fe00194e712d4e6baa | |
| parent | 2e4f490b31272a2df73d4ba23aad7f5a8ca49a2f (diff) | |
| download | go-a50c3ffbd47e3dcfc1b5bd2a2d19d55731481eaa.tar.gz go-a50c3ffbd47e3dcfc1b5bd2a2d19d55731481eaa.zip | |
cmd/internal/obj/riscv,cmd/link: shorten the riscv64 call sequence
Now that the other dependent offset has been identified, we can remove the
unnecessary ADDI instruction from the riscv64 call sequence (reducing it
to AUIPC+JALR, rather than the previous AUIPC+ADDI+JALR).
Change-Id: I348c4efb686f9f71ed1dd1d25fb9142a41230b0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/216798
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
| -rw-r--r-- | src/cmd/internal/obj/riscv/obj.go | 9 | ||||
| -rw-r--r-- | src/cmd/link/internal/ld/pcln.go | 4 | ||||
| -rw-r--r-- | src/runtime/asm_riscv64.s | 5 |
3 files changed, 4 insertions, 14 deletions
diff --git a/src/cmd/internal/obj/riscv/obj.go b/src/cmd/internal/obj/riscv/obj.go index e90769eb20..1d2c498110 100644 --- a/src/cmd/internal/obj/riscv/obj.go +++ b/src/cmd/internal/obj/riscv/obj.go @@ -55,15 +55,6 @@ func jalrToSym(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc, lr int16) *ob p.Mark |= NEED_PCREL_ITYPE_RELOC p = obj.Appendp(p, newprog) - // TODO(jsing): This instruction is not necessary, as the lower bits - // of the immediate can be encoded directly in the JALR instruction. - // However, other code currently depends on jalrToSym being 12 bytes... - p.As = AADDI - p.From = obj.Addr{Type: obj.TYPE_CONST} - p.Reg = REG_TMP - p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP} - p = obj.Appendp(p, newprog) - // Leave Sym only for the CALL reloc in assemble. p.As = AJALR p.From.Type = obj.TYPE_REG diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go index 7cba9bde6d..db44c0292e 100644 --- a/src/cmd/link/internal/ld/pcln.go +++ b/src/cmd/link/internal/ld/pcln.go @@ -271,8 +271,8 @@ func (ctxt *Link) pclntab() { case sys.RISCV64: // TODO(jsing): The JALR instruction is marked with // R_CALLRISCV, whereas the actual reloc is currently - // two instructions earlier for the AUIPC+AADI sequence. - deferreturn -= 8 + // one instruction earlier starting with the AUIPC. + deferreturn -= 4 case sys.S390X: deferreturn -= 2 default: diff --git a/src/runtime/asm_riscv64.s b/src/runtime/asm_riscv64.s index 444e2bba1b..31dc94ce54 100644 --- a/src/runtime/asm_riscv64.s +++ b/src/runtime/asm_riscv64.s @@ -254,12 +254,11 @@ TEXT runtime·gogo(SB), NOSPLIT, $16-8 // func jmpdefer(fv *funcval, argp uintptr) // called from deferreturn // 1. grab stored return address from the caller's frame -// 2. sub 12 bytes to get back to JAL deferreturn +// 2. sub 8 bytes to get back to JAL deferreturn // 3. JMP to fn -// TODO(sorear): There are shorter jump sequences. This function will need to be updated when we use them. TEXT runtime·jmpdefer(SB), NOSPLIT|NOFRAME, $0-16 MOV 0(X2), RA - ADD $-12, RA + ADD $-8, RA MOV fv+0(FP), CTXT MOV argp+8(FP), X2 |