runtime: avoid r9/r10 during memmove

Fixes #3718.

Requires CL 6300043.

R=rsc, minux.ma, extraterrestrial.neighbour
CC=golang-dev
https://golang.org/cl/6305100

diff --git a/src/pkg/runtime/memmove_arm.s b/src/pkg/runtime/memmove_arm.s
index 5c0e5740421e26945d300367f1a8082cb7de59d6..c5d7e9d70cfecae871f0f7944d44cf0776d6a74e 100644 (file)
--- a/src/pkg/runtime/memmove_arm.s
+++ b/src/pkg/runtime/memmove_arm.s
@@ -23,19 +23,40 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+// TE or TS are spilled to the stack during bulk register moves.
 TS = 0
-TE = 1
-FROM = 2
-N = 3
-TMP = 3                                        /* N and TMP don't overlap */
-TMP1 = 4
-
-// TODO(kaib): This can be done with the existing registers of LR is re-used. Same for memset.
-TEXT runtime·memmove(SB), 7, $8
-       // save g and m
-       MOVW    R9, 4(R13)
-       MOVW    R10, 8(R13)
-
+TE = 8
+
+// Warning: the linker will use R11 to synthesize certain instructions. Please
+// take care and double check with objdump.
+FROM = 11
+N = 12
+TMP = 12                               /* N and TMP don't overlap */
+TMP1 = 5
+
+RSHIFT = 5
+LSHIFT = 6
+OFFSET = 7
+
+BR0 = 0                                        /* shared with TS */
+BW0 = 1
+BR1 = 1
+BW1 = 2
+BR2 = 2
+BW2 = 3
+BR3 = 3
+BW3 = 4
+
+FW0 = 1
+FR0 = 2
+FW1 = 2
+FR1 = 3
+FW2 = 3
+FR2 = 4
+FW3 = 4
+FR3 = 8                                        /* shared with TE */
+
+TEXT runtime·memmove(SB), 7, $4
 _memmove:
        MOVW    to+0(FP), R(TS)
        MOVW    from+4(FP), R(FROM)
@@ -64,15 +85,17 @@ _b4aligned:                         /* is source now aligned? */
        BNE     _bunaligned
 
        ADD     $31, R(TS), R(TMP)      /* do 32-byte chunks if possible */
+       MOVW    R(TS), savedts+4(SP)
 _b32loop:
        CMP     R(TMP), R(TE)
        BLS     _b4tail
 
-       MOVM.DB.W (R(FROM)), [R4-R11]
-       MOVM.DB.W [R4-R11], (R(TE))
+       MOVM.DB.W (R(FROM)), [R0-R7]
+       MOVM.DB.W [R0-R7], (R(TE))
        B       _b32loop
 
 _b4tail:                               /* do remaining words if possible */
+       MOVW    savedts+4(SP), R(TS)
        ADD     $3, R(TS), R(TMP)
 _b4loop:
        CMP     R(TMP), R(TE)
@@ -107,22 +130,24 @@ _f4aligned:                               /* is source now aligned? */
        BNE     _funaligned
 
        SUB     $31, R(TE), R(TMP)      /* do 32-byte chunks if possible */
+       MOVW    R(TE), savedte+4(SP)
 _f32loop:
        CMP     R(TMP), R(TS)
        BHS     _f4tail
 
-       MOVM.IA.W (R(FROM)), [R4-R11] 
-       MOVM.IA.W [R4-R11], (R(TS))
+       MOVM.IA.W (R(FROM)), [R1-R8] 
+       MOVM.IA.W [R1-R8], (R(TS))
        B       _f32loop
 
 _f4tail:
+       MOVW    savedte+4(SP), R(TE)
        SUB     $3, R(TE), R(TMP)       /* do remaining words if possible */
 _f4loop:
        CMP     R(TMP), R(TS)
        BHS     _f1tail
 
        MOVW.P  4(R(FROM)), R(TMP1)     /* implicit write back */
-       MOVW.P  R4, 4(R(TS))            /* implicit write back */
+       MOVW.P  R(TMP1), 4(R(TS))       /* implicit write back */
        B       _f4loop
 
 _f1tail:
@@ -134,25 +159,9 @@ _f1tail:
        B       _f1tail
 
 _return:
-       // restore g and m
-       MOVW    4(R13), R9
-       MOVW    8(R13), R10
        MOVW    to+0(FP), R0
        RET
 
-RSHIFT = 4
-LSHIFT = 5
-OFFSET = 6
-
-BR0 = 7
-BW0 = 8
-BR1 = 8
-BW1 = 9
-BR2 = 9
-BW2 = 10
-BR3 = 10
-BW3 = 11
-
 _bunaligned:
        CMP     $2, R(TMP)              /* is R(TMP) < 2 ? */
 
@@ -172,7 +181,8 @@ _bunaligned:
        CMP     R(TMP), R(TE)
        BLS     _b1tail
 
-       AND     $~0x03, R(FROM)         /* align source */
+       BIC     $3, R(FROM)             /* align source */
+       MOVW    R(TS), savedts+4(SP)
        MOVW    (R(FROM)), R(BR0)       /* prime first block register */
 
 _bu16loop:
@@ -196,18 +206,10 @@ _bu16loop:
        B       _bu16loop
 
 _bu1tail:
+       MOVW    savedts+4(SP), R(TS)
        ADD     R(OFFSET), R(FROM)
        B       _b1tail
 
-FW0 = 7
-FR0 = 8
-FW1 = 8
-FR1 = 9
-FW2 = 9
-FR2 = 10
-FW3 = 10
-FR3 = 11
-
 _funaligned:
        CMP     $2, R(TMP)
 
@@ -227,7 +229,8 @@ _funaligned:
        CMP     R(TMP), R(TS)
        BHS     _f1tail
 
-       AND     $~0x03, R(FROM)         /* align source */
+       BIC     $3, R(FROM)             /* align source */
+       MOVW    R(TE), savedte+4(SP)
        MOVW.P  4(R(FROM)), R(FR3)      /* prime last block register, implicit write back */
 
 _fu16loop:
@@ -235,7 +238,7 @@ _fu16loop:
        BHS     _fu1tail
 
        MOVW    R(FR3)>>R(RSHIFT), R(FW0)
-       MOVM.IA.W (R(FROM)), [R(FR0)-R(FR3)]
+       MOVM.IA.W (R(FROM)), [R(FR0),R(FR1),R(FR2),R(FR3)]
        ORR     R(FR0)<<R(LSHIFT), R(FW0)
 
        MOVW    R(FR0)>>R(RSHIFT), R(FW1)
@@ -247,9 +250,10 @@ _fu16loop:
        MOVW    R(FR2)>>R(RSHIFT), R(FW3)
        ORR     R(FR3)<<R(LSHIFT), R(FW3)
 
-       MOVM.IA.W [R(FW0)-R(FW3)], (R(TS))
+       MOVM.IA.W [R(FW0),R(FW1),R(FW2),R(FW3)], (R(TS))
        B       _fu16loop
 
 _fu1tail:
+       MOVW    savedte+4(SP), R(TE)
        SUB     R(OFFSET), R(FROM)
        B       _f1tail