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[PATCH 1/2] opcodes: LoongArch: make all non-native jumps desugar to canonical b{lt/ge}[u] forms

WANG Xuerui i.swmail@xen0n.name
Fri Jul 29 09:42:40 GMT 2022 
On 2022/7/29 09:18, liuzhensong wrote:
>
>
> On 2022/7/27 下午7:07, WANG Xuerui wrote:
>> From: WANG Xuerui<git@xen0n.name>
>>
>> Also re-order the jump/branch opcodes while at it, so that insns are
>> sorted in ascending order according to opcodes, and the label form
>> preceding the real definition.
>> ---
>>   opcodes/loongarch-opc.c | 31 ++++++++++++-------------------
>>   1 file changed, 12 insertions(+), 19 deletions(-)
>>
>> diff --git a/opcodes/loongarch-opc.c b/opcodes/loongarch-opc.c
>> index 08ba101a902..6f5e42d57e5 100644
>> --- a/opcodes/loongarch-opc.c
>> +++ b/opcodes/loongarch-opc.c
>> @@ -810,22 +810,13 @@ static struct loongarch_opcode loongarch_float_jmp_opcodes[] =
>>   static struct loongarch_opcode loongarch_jmp_opcodes[] =
>>   {
>>     /* match,	mask,		name,		format,				macro,			include, exclude, pinfo.  */
>> -  { 0x0,	0x0,		"bltz",		"r,la",				"bltz %1,%%b16(%2)",		0, 0, 0 },
>> -  { 0x60000000, 0xfc00001f,	"bltz",		"r5:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"bgtz",		"r,la",				"bgtz %1,%%b16(%2)",		0, 0, 0 },
>> -  { 0x60000000, 0xfc0003e0,	"bgtz",		"r0:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"bgez",		"r,la",				"bgez %1,%%b16(%2)",		0, 0, 0 },
>> -  { 0x64000000, 0xfc00001f,	"bgez",		"r5:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"blez",		"r,la",				"blez %1,%%b16(%2)",		0, 0, 0 },
>> -  { 0x64000000, 0xfc0003e0,	"blez",		"r0:5,sb10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"beqz",		"r,la",				"beqz %1,%%b21(%2)",		0, 0, 0 },
>>     { 0x40000000, 0xfc000000,	"beqz",		"r5:5,sb0:5|10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"bnez",		"r,la",				"bnez %1,%%b21(%2)",		0, 0, 0 },
>>     { 0x44000000, 0xfc000000,	"bnez",		"r5:5,sb0:5|10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"jr",		"r",				"jirl $r0,%1,0",		0, 0, 0 },
>> -  { 0x50000000, 0xfc000000,	"b",		"sb0:10|10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"b",		"la",				"b %%b26(%1)",			0, 0, 0 },
>>     { 0x4c000000, 0xfc000000,	"jirl",		"r0:5,r5:5,s10:16<<2",		0,				0, 0, 0 },
>> +  { 0x0,	0x0,		"b",		"la",				"b %%b26(%1)",			0, 0, 0 },
>> +  { 0x50000000, 0xfc000000,	"b",		"sb0:10|10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"bl",		"la",				"bl %%b26(%1)",			0, 0, 0 },
>>     { 0x54000000, 0xfc000000,	"bl",		"sb0:10|10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"beq",		"r,r,la",			"beq %1,%2,%%b16(%3)",		0, 0, 0 },
>> @@ -834,20 +825,22 @@ static struct loongarch_opcode loongarch_jmp_opcodes[] =
>>     { 0x5c000000, 0xfc000000,	"bne",		"r5:5,r0:5,sb10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"blt",		"r,r,la",			"blt %1,%2,%%b16(%3)",		0, 0, 0 },
>>     { 0x60000000, 0xfc000000,	"blt",		"r5:5,r0:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"bgt",		"r,r,la",			"bgt %1,%2,%%b16(%3)",		0, 0, 0 },
>> -  { 0x60000000, 0xfc000000,	"bgt",		"r0:5,r5:5,sb10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"bge",		"r,r,la",			"bge %1,%2,%%b16(%3)",		0, 0, 0 },
>>     { 0x64000000, 0xfc000000,	"bge",		"r5:5,r0:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"ble",		"r,r,la",			"ble %1,%2,%%b16(%3)",		0, 0, 0 },
>> -  { 0x64000000, 0xfc000000,	"ble",		"r0:5,r5:5,sb10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"bltu",		"r,r,la",			"bltu %1,%2,%%b16(%3)",		0, 0, 0 },
>>     { 0x68000000, 0xfc000000,	"bltu",		"r5:5,r0:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"bgtu",		"r,r,la",			"bgtu %1,%2,%%b16(%3)",		0, 0, 0 },
>> -  { 0x68000000, 0xfc000000,	"bgtu",		"r0:5,r5:5,sb10:16<<2",		0,				0, 0, 0 },
>>     { 0x0,	0x0,		"bgeu",		"r,r,la",			"bgeu %1,%2,%%b16(%3)",		0, 0, 0 },
>>     { 0x6c000000, 0xfc000000,	"bgeu",		"r5:5,r0:5,sb10:16<<2",		0,				0, 0, 0 },
>> -  { 0x0,	0x0,		"bleu",		"r,r,la",			"bleu %1,%2,%%b16(%3)",		0, 0, 0 },
>> -  { 0x6c000000, 0xfc000000,	"bleu",		"r0:5,r5:5,sb10:16<<2",		0,				0, 0, 0 },
>> +  /* Jumps implemented with macros.  */
>> +  { 0x0,	0x0,		"bgt",		"r,r,la",			"blt %2,%1,%%b16(%3)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"ble",		"r,r,la",			"bge %2,%1,%%b16(%3)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"bltz",		"r,la",				"blt %1,$r0,%%b16(%2)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"bgtz",		"r,la",				"blt $r0,%1,%%b16(%2)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"bgez",		"r,la",				"bge %1,$r0,%%b16(%2)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"blez",		"r,la",				"bge $r0,%1,%%b16(%2)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"bgtu",		"r,r,la",			"bltu %2,%1,%%b16(%3)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"bleu",		"r,r,la",			"bgeu %2,%1,%%b16(%3)",		0, 0, 0 },
>> +  { 0x0,	0x0,		"jr",		"r",				"jirl $r0,%1,0",		0, 0, 0 },
>>     { 0 } /* Terminate the list.  */
>>   };
>>   
> Looks good to me.  And I don't think the instruction "ret" is 
> necessary in [PATCH 2/2].

Please don't be so subjective. You and Chenghua never gave objective 
reasons against "ret", your rejections seem to be just based on some 
kind of personal preference. All while ignoring the objective 
readability improvement and ease of learning gained by adding such 
support, and I believe there must be community members in favor of the 
addition.

And it's not like everyone must immediately migrate to it, people may 
well continue to write "jr ra" or even "jirl zero, ra, 0", only those of 
us preferring brevity would have one more palatable choice...
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