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[PATCH][ARM][2/4] Fix operand costing logic for SMUL[TB][TB]
- From: Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Ramana Radhakrishnan <ramana dot radhakrishnan at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Jim Wilson <jim dot wilson at linaro dot org>
- Date: Fri, 22 Jan 2016 09:52:31 +0000
- Subject: [PATCH][ARM][2/4] Fix operand costing logic for SMUL[TB][TB]
- Authentication-results: sourceware.org; auth=none
Hi all,
As part of investigating the codegen effects of a fix for PR 65932 I found we assign
too high a cost for the sign-extending multiply instruction SMULBB.
This is because we add the cost of a multiply-extend but then also recurse into the
SIGN_EXTEND sub-expressions rather than the registers (or subregs) being sign-extended.
This patch is a simple fix. The fix is right by itself, but in combination with patch 3
fix the gcc.target/arm/wmul-2.c testcase.
Bootstrapped and tested on arm-none-linux-gnueabihf.
Ok for trunk?
Thanks,
Kyrill
2016-01-22 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* config/arm/arm.c (arm_new_rtx_costs, MULT case): Properly extract
the operands of the SIGN_EXTENDs from a SMUL[TB][TB] rtx.
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 17f00b5a1de21de35366b82040a7ad46d65f899e..ee3ebe4561ea3d9791fabdfcec8b16af63bd4d20 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -10321,8 +10321,10 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum rtx_code outer_code,
/* SMUL[TB][TB]. */
if (speed_p)
*cost += extra_cost->mult[0].extend;
- *cost += rtx_cost (XEXP (x, 0), mode, SIGN_EXTEND, 0, speed_p);
- *cost += rtx_cost (XEXP (x, 1), mode, SIGN_EXTEND, 1, speed_p);
+ *cost += rtx_cost (XEXP (XEXP (x, 0), 0), mode,
+ SIGN_EXTEND, 0, speed_p);
+ *cost += rtx_cost (XEXP (XEXP (x, 1), 0), mode,
+ SIGN_EXTEND, 1, speed_p);
return true;
}
if (speed_p)