| Message ID | 20100817144925.GA26996@intel.com |
|---|---|
| State | New |
| Headers | show |
On 08/17/2010 04:49 PM, H.J. Lu wrote: > We added ix86_lea_for_add_ok and modified *add<mode>_1 to make sure > that we use LEA on address and ADD on non-address for TARGET_OPT_AGU. > It turned out ADD is always faster than LEA on all processors, except for > TARGET_OPT_AGU. This patch changes *add<mode>_1 and ix86_lea_for_add_ok > to avoid lea for !TARGET_OPT_AGU processors. OK for trunk? Yes, looks better. Thanks. Bernd
On 08/17/2010 07:49 AM, H.J. Lu wrote: > default: > - /* Use add as much as possible to replace lea for AGU optimization. */ > - if (which_alternative == 2 && TARGET_OPT_AGU) > + /* This alternative was added for TARGET_OPT_AGU to use add as > + much as possible. But add is also faster than lea for > + !TARGET_OPT_AGU. */ > + if (which_alternative == 2) > return "add{<imodesuffix>}\t{%1, %0|%0, %1}"; > > gcc_assert (rtx_equal_p (operands[0], operands[1])); > @@ -5825,10 +5827,7 @@ > } > } > [(set (attr "type") > - (cond [(and (eq_attr "alternative" "2") > - (eq (symbol_ref "TARGET_OPT_AGU") (const_int 0))) > - (const_string "lea") > - (eq_attr "alternative" "3") > + (cond [(eq_attr "alternative" "3") > (const_string "lea") > (match_operand:SWI48 2 "incdec_operand" "") > (const_string "incdec") Is there any reason not to remove alternative 2 now that you're not doing anything special with it? r~
On 08/17/2010 05:18 PM, Richard Henderson wrote: > Is there any reason not to remove alternative 2 now that > you're not doing anything special with it? If I understood things correctly, the problem was that in this case we'd match what is now alternative 3, and generate lea. Bernd
On 08/17/2010 08:20 AM, Bernd Schmidt wrote: > On 08/17/2010 05:18 PM, Richard Henderson wrote: >> Is there any reason not to remove alternative 2 now that >> you're not doing anything special with it? > > If I understood things correctly, the problem was that in this case we'd > match what is now alternative 3, and generate lea. Ah, right, I see. The patch is ok. r~
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index b925122..f1d4402 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -14802,10 +14802,10 @@ distance_agu_use (unsigned int regno0, rtx insn) #define IX86_LEA_PRIORITY 2 /* Return true if it is ok to optimize an ADD operation to LEA - operation to avoid flag register consumation. For the processors - like ATOM, if the destination register of LEA holds an actual - address which will be used soon, LEA is better and otherwise ADD - is better. */ + operation to avoid flag register consumation. For most processors, + ADD is faster than LEA. For the processors like ATOM, if the + destination register of LEA holds an actual address which will be + used soon, LEA is better and otherwise ADD is better. */ bool ix86_lea_for_add_ok (enum rtx_code code ATTRIBUTE_UNUSED, @@ -14813,16 +14813,14 @@ ix86_lea_for_add_ok (enum rtx_code code ATTRIBUTE_UNUSED, { unsigned int regno0 = true_regnum (operands[0]); unsigned int regno1 = true_regnum (operands[1]); - unsigned int regno2; - - if (!TARGET_OPT_AGU || optimize_function_for_size_p (cfun)) - return regno0 != regno1; - - regno2 = true_regnum (operands[2]); + unsigned int regno2 = true_regnum (operands[2]); /* If a = b + c, (a!=b && a!=c), must use lea form. */ if (regno0 != regno1 && regno0 != regno2) return true; + + if (!TARGET_OPT_AGU || optimize_function_for_size_p (cfun)) + return false; else { int dist_define, dist_use; diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md index 0041158..f6ab0e2 100644 --- a/gcc/config/i386/i386.md +++ b/gcc/config/i386/i386.md @@ -5813,8 +5813,10 @@ } default: - /* Use add as much as possible to replace lea for AGU optimization. */ - if (which_alternative == 2 && TARGET_OPT_AGU) + /* This alternative was added for TARGET_OPT_AGU to use add as + much as possible. But add is also faster than lea for + !TARGET_OPT_AGU. */ + if (which_alternative == 2) return "add{<imodesuffix>}\t{%1, %0|%0, %1}"; gcc_assert (rtx_equal_p (operands[0], operands[1])); @@ -5825,10 +5827,7 @@ } } [(set (attr "type") - (cond [(and (eq_attr "alternative" "2") - (eq (symbol_ref "TARGET_OPT_AGU") (const_int 0))) - (const_string "lea") - (eq_attr "alternative" "3") + (cond [(eq_attr "alternative" "3") (const_string "lea") (match_operand:SWI48 2 "incdec_operand" "") (const_string "incdec")