Re: MD file patterns and RTL templates

1 msg	gcc and profiling
2 msg	libstdc++.so.6
5 msg	gcc exception handle
5 msg	Re: gcc 4.1.1: char *p = 'str' puts 'str' into ...
2 msg	compiling xmmintrin.h
1 msg	less strict type checking within template code
4 msg	online doc on debugging formats?
2 msg	warning: assignment makes pointer from integer ...
1 msg	Problems in building gcc 4.0.3

MD file patterns and RTL templates
\ BHASKAR G. REDDY (27 Jan 2007)
. \ Rask Ingemann Lambertsen (27 Jan 2007)

5 msg	question about the -I option
3 msg	Can C and C++ object files be linked into an ex...
2 msg	Renesas H8S
3 msg	C++ 'export' keyword
1 msg	Building gcj with enable-libgcj-debug.
2 msg	define_split question
1 msg	4.0.3 warning
1 msg	Known problem with gcc 4.0.3 on sparc solaris t...
8 msg	gcc-4.1.1 - build fail
1 msg	Building gcc 2.8.1 on AIX 5.3

Subject:	Re: MD file patterns and RTL templates
Group:	Gcc-help
From:	Rask Ingemann Lambertsen
Date:	27 Jan 2007

On Sat, Jan 27, 2007 at 11:13:28PM +0530, BHASKAR G. REDDY wrote:
>
> Hi,
> Is there any way to know, how a pattern in MD file is matched while
> generating code?

The program build/genrecog.c is compiled and run, generating insn-recog.c
which contains a decision tree to match RTL against the instruction patterns
in the machine description.

> But there are numerous other patterns in this md file which also
> generates and instruction when matched against RTL template.

It is quite normal since "andl" also sets the condition codes. This alone
makes for three patterns to output an "andl" instruction: One to describe
what happens to the destination operand, one to describe how the condition
codes are set and one to describe both of the above at the same time.
Additionally, "andl" may be used for clearing bit-fields.

--
Rask Ingemann Lambertsen