math/mpx-mul4-amd64-sse2.S: Save a spill by better register allocation.

[catacomb] / math / mpx-mul4-amd64-sse2.S

diff --git a/math/mpx-mul4-amd64-sse2.S b/math/mpx-mul4-amd64-sse2.S
index a37aba6..da3e6d6 100644 (file)
--- a/math/mpx-mul4-amd64-sse2.S
+++ b/math/mpx-mul4-amd64-sse2.S
@@ -1155,7 +1155,7 @@ FUNC(mpxmont_redc4_amd64_sse2)
        // outer loop dv        r10     rcx
        // outer loop dv limit  r11     r11
        // nv base              rdx     r8
-       // nv limit             r9      r12*
+       // nv limit             r9      r10*
        // n                    rcx     r9
        // c                    rcx     r9
 
@@ -1183,14 +1183,13 @@ FUNC(mpxmont_redc4_amd64_sse2)
 #  define DV rcx
 #  define DVLO r11
 #  define NV r8
-#  define NVL r12
+#  define NVL r10
 #  define N r9
 #  define C r9d
 
        pushreg rbx
        pushreg rdi
-       pushreg r12
-       stalloc 160
+       stalloc 168
 
        savexmm xmm6,    0
        savexmm xmm7,   16
@@ -1260,7 +1259,9 @@ FUNC(mpxmont_redc4_amd64_sse2)
        cmp     rdi, DVL4
        jb      0b
 
-       // Deal with the tail end.
+       // Deal with the tail end.  Note that the actual destination length
+       // won't be an exacty number of blocks of four, so it's safe to just
+       // drop through here.
 7:     add     [rdi], C
        mov     C, 0
        add     rdi, 4
@@ -1268,9 +1269,7 @@ FUNC(mpxmont_redc4_amd64_sse2)
        cmp     rdi, DVL
        jb      7b
 
-       // All done for this iteration.  Start the next.  (This must have at
-       // least one follow-on iteration, or we'd not have started this outer
-       // loop.)
+       // All done for this iteration.  Start the next.
 8:     mov     rdi, DV                 // -> Z = dv[i]
        mov     rbx, NV                 // -> X = nv[0]
        cmp     rdi, DVLO               // all done yet?
@@ -1300,8 +1299,7 @@ FUNC(mpxmont_redc4_amd64_sse2)
        rstrxmm xmm14, 128
        rstrxmm xmm15, 144
 
-       stfree  160
-       popreg  r12
+       stfree  168
        popreg  rdi
        popreg  rbx
 #endif