From: Richard Henderson <richard.henderson@linaro.org> Date: Fri, 29 Jan 2021 20:00:42 +0000 (-1000) Subject: tcg/tci: Improve tcg_target_call_clobber_regs X-Git-Tag: v6.1.0~114^2~24 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=b6139eb0578;p=qemu-nvme.git tcg/tci: Improve tcg_target_call_clobber_regs The current setting is much too pessimistic. Indicating only the one or two registers that are actually assigned after a call should avoid unnecessary movement between the register array and the stack array. Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- diff --git a/tcg/tci/tcg-target.c.inc b/tcg/tci/tcg-target.c.inc index 823ecd5d35..8f3f9ef7d3 100644 --- a/tcg/tci/tcg-target.c.inc +++ b/tcg/tci/tcg-target.c.inc @@ -810,8 +810,14 @@ static void tcg_target_init(TCGContext *s) tcg_target_available_regs[TCG_TYPE_I32] = BIT(TCG_TARGET_NB_REGS) - 1; /* Registers available for 64 bit operations. */ tcg_target_available_regs[TCG_TYPE_I64] = BIT(TCG_TARGET_NB_REGS) - 1; - /* TODO: Which registers should be set here? */ - tcg_target_call_clobber_regs = BIT(TCG_TARGET_NB_REGS) - 1; + /* + * The interpreter "registers" are in the local stack frame and + * cannot be clobbered by the called helper functions. However, + * the interpreter assumes a 64-bit return value and assigns to + * the return value registers. + */ + tcg_target_call_clobber_regs = + MAKE_64BIT_MASK(TCG_REG_R0, 64 / TCG_TARGET_REG_BITS); s->reserved_regs = 0; tcg_regset_set_reg(s->reserved_regs, TCG_REG_CALL_STACK);