From 15b4c567c5a1fc40aa6d9de04cc5becc32df3641 Mon Sep 17 00:00:00 2001 From: patacongo Date: Thu, 13 Nov 2008 00:15:08 +0000 Subject: No need to restore r8-r14 on return from int if no context switch git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1213 42af7a65-404d-4744-a932-0658087f49c3 --- nuttx/arch/sh/src/sh1/sh1_vector.S | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/nuttx/arch/sh/src/sh1/sh1_vector.S b/nuttx/arch/sh/src/sh1/sh1_vector.S index 3e6a32029..9e7ef5075 100644 --- a/nuttx/arch/sh/src/sh1/sh1_vector.S +++ b/nuttx/arch/sh/src/sh1/sh1_vector.S @@ -345,7 +345,7 @@ _up_vector: mov.l .Ldoirq, r0 jsr @r0 - mov r15, r14 + nop /* Recover the user stack point */ @@ -355,7 +355,7 @@ _up_vector: mov.l .Ldoirq, r0 jsr @r0 - mov r15, r14 + nop #endif /* On return, R0 holds the address of the base of the XCPTCONTEXT * structure to use for the return -- may not be the same as the @@ -368,17 +368,28 @@ _up_vector: bf .Lcontextswitch mov r0, r15 - /* Restore registers from the stack. */ + /* Restore registers from the stack. NOTE: We coudl improve interrupt + * performance by skipping the restore of r8-r14. These will not + * be modified by the called C code + */ - mov.l @r15+, r8 /* 0-8: r8-r14, pr, and gbr */ +#if 1 + /* Skip over static registers -- these will not be modified by the + * called C code (r8-r14) + */ + + add #(7*4), r15 /* 0-6: Skip over r8-r14 */ +#else + mov.l @r15+, r8 /* 0-6: r8-r14 */ mov.l @r15+, r9 mov.l @r15+, r10 mov.l @r15+, r11 mov.l @r15+, r12 mov.l @r15+, r13 mov.l @r15+, r14 +#endif - lds.l @r15+, pr + lds.l @r15+, pr /* 7-8: pr and gbr */ ldc.l @r15+, gbr add #4, r15 /* 9: Skip SP restore */ -- cgit v1.2.3