Compile-time tuning: assembly phase
Not as much compile-time gain from reworking the assembly phase as I'd
hoped, but still worthwhile. Should see ~2% improvement thanks to
the assembly rework. On the other hand, expect some huge gains for some
application thanks to better detection of large machine-generated init
methods. Thinkfree shows a 25% improvement.
The major assembly change was to establish thread the LIR nodes that
require fixup into a fixup chain. Only those are processed during the
final assembly pass(es). This doesn't help for methods which only
require a single pass to assemble, but does speed up the larger methods
which required multiple assembly passes.
Also replaced the block_map_ basic block lookup table (which contained
space for a BasicBlock* for each dex instruction unit) with a block id
map - cutting its space requirements by half in a 32-bit pointer
environment.
Changes:
o Reduce size of LIR struct by 12.5% (one of the big memory users)
o Repurpose the use/def portion of the LIR after optimization complete.
o Encode instruction bits to LIR
o Thread LIR nodes requiring pc fixup
o Change follow-on assembly passes to only consider fixup LIRs
o Switch on pc-rel fixup kind
o Fast-path for small methods - single pass assembly
o Avoid using cb[n]z for null checks (almost always exceed displacement)
o Improve detection of large initialization methods.
o Rework def/use flag setup.
o Remove a sequential search from FindBlock using lookup table of 16-bit
block ids rather than full block pointers.
o Eliminate pcRelFixup and use fixup kind instead.
o Add check for 16-bit overflow on dex offset.
Change-Id: I4c6615f83fed46f84629ad6cfe4237205a9562b4
diff --git a/compiler/dex/quick/arm/arm_lir.h b/compiler/dex/quick/arm/arm_lir.h
index 2f54190..d184673 100644
--- a/compiler/dex/quick/arm/arm_lir.h
+++ b/compiler/dex/quick/arm/arm_lir.h
@@ -462,7 +462,7 @@
// Instruction assembly field_loc kind.
enum ArmEncodingKind {
- kFmtUnused,
+ kFmtUnused, // Unused field and marks end of formats.
kFmtBitBlt, // Bit string using end/start.
kFmtDfp, // Double FP reg.
kFmtSfp, // Single FP reg.
@@ -477,6 +477,7 @@
kFmtBrOffset, // Signed extended [26,11,13,21-16,10-0]:0.
kFmtFPImm, // Encoded floating point immediate.
kFmtOff24, // 24-bit Thumb2 unconditional branch encoding.
+ kFmtSkip, // Unused field, but continue to next.
};
// Struct used to define the snippet positions for each Thumb opcode.
@@ -492,6 +493,7 @@
const char* name;
const char* fmt;
int size; // Note: size is in bytes.
+ FixupKind fixup;
};
} // namespace art