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 <f4...@amsat.org>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
tcg/tci/tcg-target.c.inc | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
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);
--
2.25.1
