On 28/08/13 08:00, bin.cheng wrote:
> Hi,
>
> This patch refines scaled address expression on ARM. It supports
> "base+index*scale" in arm_legitimate_address_outer_p. It also tries to
> legitimize "base + index * scale + offset" with "reg <- base + offset; reg
> + index * scale" by introducing thumb2_legitimize_address. For now function
> thumb2_legitimize_address is a kind of placeholder and just does the
> mentioned transformation by calling to try_multiplier_address. Hoping we
> can improve it in the future.
>
> With this patch:
> 1) "base+index*scale" is recognized.
That's because (PLUS (REG) (MULT (REG) (CONST))) is not canonical form.
So this shouldn't be necessary. Can you identify where this
non-canoncial form is being generated?
R.
> 2) PR57540 is fixed.
>
> Bootstrapped and Tested on A15. Is it OK?
>
> Thanks.
> Bin
>
> 2013-08-28 Bin Cheng <bin.ch...@arm.com>
>
> * config/arm/arm.c (arm_legitimate_address_outer_p):
> Support addressing mode like "base + index * scale".
> (try_multiplier_address): New function.
> (arm_legitimize_address): Call try_multiplier_address.
>
>
> 6-arm-scaled_address-20130828.txt
>
>
> Index: gcc/config/arm/arm.c
> ===================================================================
> --- gcc/config/arm/arm.c (revision 200774)
> +++ gcc/config/arm/arm.c (working copy)
> @@ -5931,7 +5931,9 @@ arm_legitimate_address_outer_p (enum machine_mode
> && arm_legitimate_index_p (mode, xop1, outer, strict_p))
> || (!strict_p && will_be_in_index_register (xop1))))
> || (arm_address_register_rtx_p (xop1, strict_p)
> - && arm_legitimate_index_p (mode, xop0, outer, strict_p)));
> + && arm_legitimate_index_p (mode, xop0, outer, strict_p))
> + || (arm_address_register_rtx_p (xop0, strict_p)
> + && arm_legitimate_index_p (mode, xop1, outer, strict_p)));
> }
>
> #if 0
> @@ -6652,6 +6654,106 @@ legitimize_tls_address (rtx x, rtx reg)
> }
> }
>
> +/* Try to find address expression like base + index * scale + offset
> + in X. If we find one, force base + offset into register and
> + construct new expression reg + index * scale; return the new
> + address expression if it's valid. Otherwise return X. */
> +static rtx
> +try_multiplier_address (rtx x, enum machine_mode mode ATTRIBUTE_UNUSED)
> +{
> + rtx tmp, base_reg, new_rtx;
> + rtx base = NULL_RTX, index = NULL_RTX, scale = NULL_RTX, offset = NULL_RTX;
> +
> + gcc_assert (GET_CODE (x) == PLUS);
> +
> + /* Try to find and record base/index/scale/offset in X. */
> + if (GET_CODE (XEXP (x, 1)) == MULT)
> + {
> + tmp = XEXP (x, 0);
> + index = XEXP (XEXP (x, 1), 0);
> + scale = XEXP (XEXP (x, 1), 1);
> + if (GET_CODE (tmp) != PLUS)
> + return x;
> +
> + base = XEXP (tmp, 0);
> + offset = XEXP (tmp, 1);
> + }
> + else
> + {
> + tmp = XEXP (x, 0);
> + offset = XEXP (x, 1);
> + if (GET_CODE (tmp) != PLUS)
> + return x;
> +
> + base = XEXP (tmp, 0);
> + scale = XEXP (tmp, 1);
> + if (GET_CODE (base) == MULT)
> + {
> + tmp = base;
> + base = scale;
> + scale = tmp;
> + }
> + if (GET_CODE (scale) != MULT)
> + return x;
> +
> + index = XEXP (scale, 0);
> + scale = XEXP (scale, 1);
> + }
> +
> + if (CONST_INT_P (base))
> + {
> + tmp = base;
> + base = offset;
> + offset = tmp;
> + }
> +
> + if (CONST_INT_P (index))
> + {
> + tmp = index;
> + index = scale;
> + scale = tmp;
> + }
> +
> + /* ARM only supports constant scale in address. */
> + if (!CONST_INT_P (scale))
> + return x;
> +
> + if (GET_MODE (base) != SImode || GET_MODE (index) != SImode)
> + return x;
> +
> + /* Only register/constant are allowed in each part. */
> + if (!symbol_mentioned_p (base)
> + && !symbol_mentioned_p (offset)
> + && !symbol_mentioned_p (index)
> + && !symbol_mentioned_p (scale))
> + {
> + /* Force "base+offset" into register and construct
> + "register+index*scale". Return the new expression
> + only if it's valid. */
> + tmp = gen_rtx_PLUS (SImode, base, offset);
> + base_reg = force_reg (SImode, tmp);
> + tmp = gen_rtx_fmt_ee (MULT, SImode, index, scale);
> + new_rtx = gen_rtx_PLUS (SImode, base_reg, tmp);
> + return new_rtx;
> + }
> +
> + return x;
> +}
> +
> +/* Try machine-dependent ways of modifying an illegitimate Thumb2 address
> + to be legitimate. If we find one, return the new address.
> +
> + TODO: legitimize_address for Thumb2. */
> +static rtx
> +thumb2_legitimize_address (rtx x, rtx orig_x ATTRIBUTE_UNUSED,
> + enum machine_mode mode)
> +{
> + if (GET_CODE (x) == PLUS)
> + return try_multiplier_address (x, mode);
> +
> + return x;
> +}
> +
> /* Try machine-dependent ways of modifying an illegitimate address
> to be legitimate. If we find one, return the new, valid address. */
> rtx
> @@ -6659,9 +6761,9 @@ arm_legitimize_address (rtx x, rtx orig_x, enum ma
> {
> if (!TARGET_ARM)
> {
> - /* TODO: legitimize_address for Thumb2. */
> if (TARGET_THUMB2)
> - return x;
> + return thumb2_legitimize_address (x, orig_x, mode);
> +
> return thumb_legitimize_address (x, orig_x, mode);
> }
>
> @@ -6673,6 +6775,10 @@ arm_legitimize_address (rtx x, rtx orig_x, enum ma
> rtx xop0 = XEXP (x, 0);
> rtx xop1 = XEXP (x, 1);
>
> + rtx new_rtx = try_multiplier_address (x, mode);
> + if (new_rtx != x)
> + return new_rtx;
> +
> if (CONSTANT_P (xop0) && !symbol_mentioned_p (xop0))
> xop0 = force_reg (SImode, xop0);
>
>
