syscall: avoid zeroing unused syscall arguments

Zeroing unused registers is not required. Removing it makes the code
very slightly smaller and very slightly faster.

Change-Id: I1ec17b497db971ca8a3641e3e94c063571419f27
GitHub-Last-Rev: f721bb263637717e8ff9fd2c34148b5b2762e8c4
GitHub-Pull-Request: golang/go#31596
Reviewed-on: https://go-review.googlesource.com/c/go/+/173160
Reviewed-by: Ian Lance Taylor <iant@golang.org>

diff --git a/src/syscall/asm_darwin_amd64.s b/src/syscall/asm_darwin_amd64.s
index eab4fcdc063adfbf982c8c2499716c74350cfce9..c863889a7138526ecb6675943ffacc11bdb8ca69 100644 (file)
--- a/src/syscall/asm_darwin_amd64.s
+++ b/src/syscall/asm_darwin_amd64.s
@@ -17,9 +17,6 @@ TEXT  ·Syscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        ADDQ    $0x2000000, AX
        SYSCALL
@@ -100,9 +97,6 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        ADDQ    $0x2000000, AX
        SYSCALL

diff --git a/src/syscall/asm_linux_amd64.s b/src/syscall/asm_linux_amd64.s
index 364815df18c15a1e97995fba1304fa0d2d761e91..2c3374338f170b2d4f43ccb991494a73289f7532 100644 (file)
--- a/src/syscall/asm_linux_amd64.s
+++ b/src/syscall/asm_linux_amd64.s
@@ -19,9 +19,6 @@ TEXT ·Syscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        SYSCALL
        CMPQ    AX, $0xfffffffffffff001
@@ -70,9 +67,6 @@ TEXT ·RawSyscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        SYSCALL
        CMPQ    AX, $0xfffffffffffff001
@@ -139,9 +133,6 @@ TEXT ·rawSyscallNoError(SB),NOSPLIT,$0-48
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        SYSCALL
        MOVQ    AX, r1+32(FP)

diff --git a/src/syscall/asm_unix_amd64.s b/src/syscall/asm_unix_amd64.s
index 025408f9e158680d9acd4ebf7941afd79c9fa8be..9cf3fe0d358fb4f72b4b65ce6ed6dbd7589ec8f8 100644 (file)
--- a/src/syscall/asm_unix_amd64.s
+++ b/src/syscall/asm_unix_amd64.s
@@ -21,9 +21,6 @@ TEXT  ·Syscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        SYSCALL
        JCC     ok
        MOVQ    $-1, r1+32(FP)  // r1
@@ -65,9 +62,6 @@ TEXT  ·RawSyscall(SB),NOSPLIT,$0-56
        MOVQ    a1+8(FP), DI
        MOVQ    a2+16(FP), SI
        MOVQ    a3+24(FP), DX
-       MOVQ    $0, R10
-       MOVQ    $0, R8
-       MOVQ    $0, R9
        MOVQ    trap+0(FP), AX  // syscall entry
        SYSCALL
        JCC     ok1