powerpc/math_emu/efp: No need to round if the result is exact

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

diff --git a/arch/powerpc/math-emu/math_efp.c b/arch/powerpc/math-emu/math_efp.c
index 10fda0f..96dbbae 100644 (file)
--- a/arch/powerpc/math-emu/math_efp.c
+++ b/arch/powerpc/math-emu/math_efp.c
@@ -676,13 +676,20 @@ int speround_handler(struct pt_regs *regs)
        type = insn_type(speinsn & 0x7ff);
        if (type == XCR) return -ENOSYS;
 
+       __FPU_FPSCR = mfspr(SPRN_SPEFSCR);
+       pr_debug("speinsn:%08lx spefscr:%08lx\n", speinsn, __FPU_FPSCR);
+
+       /* No need to round if the result is exact */
+       if (!(__FPU_FPSCR & FP_EX_INEXACT))
+               return 0;
+
        fc = (speinsn >> 21) & 0x1f;
        s_lo = regs->gpr[fc] & SIGN_BIT_S;
        s_hi = current->thread.evr[fc] & SIGN_BIT_S;
        fgpr.wp[0] = current->thread.evr[fc];
        fgpr.wp[1] = regs->gpr[fc];
 
-       __FPU_FPSCR = mfspr(SPRN_SPEFSCR);
+       pr_debug("round fgpr: %08x  %08x\n", fgpr.wp[0], fgpr.wp[1]);
 
        switch ((speinsn >> 5) & 0x7) {
        /* Since SPE instructions on E500 core can handle round to nearest
@@ -722,6 +729,8 @@ int speround_handler(struct pt_regs *regs)
        current->thread.evr[fc] = fgpr.wp[0];
        regs->gpr[fc] = fgpr.wp[1];
 
+       pr_debug("  to fgpr: %08x  %08x\n", fgpr.wp[0], fgpr.wp[1]);
+
        return 0;
 }