llvm-6502/lib/Transforms
Chris Lattner 79b3bd395d If an alloca only has two types of uses: 1) reads 2) a memcpy/memmove that
copies from a constant global, then we can change the reads to read from the
global instead of from the alloca.  This eliminates the alloca and the memcpy,
and promotes secondary optimizations (because the loads are now loads from
a constant global).

This is important for a common C idiom:

void foo() {
   int A[] = {1,2,3,4,5,6,7,8,9...};
   ... only reads of A ...
}

For some reason, people forget to mark the array static or const.

This triggers on these multisource benchmarks:
JM/ldecode: block_pos, [3 x [4 x [4 x i32]]]
FreeBench/mason: m, [18 x i32], inlined 4 times
MiBench/office-stringsearch: search_strings, [1332 x i8*]
MiBench/office-stringsearch: find_strings, [1333 x i8*]
Prolangs-C++/city: dirs, [9 x i8*], inlined 4 places

and these spec benchmarks:
177.mesa: message, [8 x [32 x i8]]
186.crafty: bias_rl45, [64 x i32]
186.crafty: diag_sq, [64 x i32]
186.crafty: empty, [9 x i8]
186.crafty: xlate, [15 x i8]
186.crafty: status, [13 x i8]
186.crafty: bdinfo, [25 x i8]
445.gobmk: routines, [16 x i8*]
458.sjeng: piece_rep, [14 x i8*]
458.sjeng: t, [13 x i32], inlined 4 places.
464.h264ref: block8x8_idx, [3 x [4 x [4 x i32]]]
464.h264ref: block_pos, [3 x [4 x [4 x i32]]]
464.h264ref: j_off_tab, [12 x i32]

This implements Transforms/ScalarRepl/memcpy-from-global.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36429 91177308-0d34-0410-b5e6-96231b3b80d8
2007-04-25 06:40:51 +00:00
..
Hello
Instrumentation remove use of BasicBlock::getNext 2007-04-17 17:54:12 +00:00
IPO Removed tabs everywhere except autogenerated & external files. Add make 2007-04-16 18:10:23 +00:00
Scalar If an alloca only has two types of uses: 1) reads 2) a memcpy/memmove that 2007-04-25 06:40:51 +00:00
Utils Fix a comment. 2007-04-21 07:12:44 +00:00
Makefile