-----Original Message-----
From: gcc-patches-ow...@gcc.gnu.org [mailto:gcc-patches-
ow...@gcc.gnu.org] On Behalf Of bin.cheng
Sent: Monday, September 02, 2013 3:09 PM
To: Richard Earnshaw
Cc: gcc-patches@gcc.gnu.org
Subject: RE: [PATCH ARM]Refine scaled address expression on ARM
-----Original Message-----
From: Richard Earnshaw
Sent: Thursday, August 29, 2013 9:06 PM
To: Bin Cheng
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH ARM]Refine scaled address expression on ARM
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?
Oh, for now ivopt constructs "index*scale" to test whether backend
supports scaled addressing mode, which is not valid on ARM, so I was going
to construct "base + index*scale" instead. Since "base + index * scale"
is not
canonical form, I will construct the canonical form and drop this part of
the
patch.
Is rest of this patch OK?
Hi Richard, I removed the part over which you concerned and created this
updated patch.
Is it OK?
Thanks.
bin
2013-09-18 Bin Cheng<bin.ch...@arm.com>
* config/arm/arm.c (try_multiplier_address): New function.
(thumb2_legitimize_address): New function.
(arm_legitimize_address): Call try_multiplier_address and
thumb2_legitimize_address.
6-arm-scaled_address-20130918.txt
Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c (revision 200774)
+++ gcc/config/arm/arm.c (working copy)
@@ -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;
