[MIR] Making MIR Printing, opt -dot-cfg, and -debug printing faster

Value::printAsOperand has been scanning the entire module just to
print a single value as an operand, regardless being asked to print a
type or not at all, and regardless really needing to scan the module
to print a type.

It made some of the users of the method exceptionally slow on large
IR-modules (or large MIR-files with large IR-modules embedded).

This patch defers scanning a module looking for struct types, mostly
numbered struct types, as much as possible, speeding up those users
w/o changing any APIs at all.

See speedup examples below:

Release Build:

# 83 seconds -> 5.5 seconds
time ./bin/llc -start-before=irtranslator -stop-after=irtranslator \
  -global-isel -global-isel-abort=2 -simplify-mir sqlite3.O0.ll -o \
  sqlite3.O0.ll.regbankselected.mir

# 133 seconds -> 6.2 seconds
time ./bin/opt sqlite3.O0.ll -dot-cfg -disable-output

Release + Asserts Build:

# 95 seconds -> 5.5 seconds
time ./bin/llc -start-before=irtranslator -stop-after=irtranslator \
  -global-isel -global-isel-abort=2 -simplify-mir sqlite3.O0.ll -o \
  sqlite3.O0.ll.regbankselected.mir

# 146 seconds -> 6.2 seconds
time ./bin/opt sqlite3.O0.ll -dot-cfg -disable-output

# 1096 seconds -> 553 seconds
time ./bin/llc -debug-only=isel -fast-isel=false -stop-after=isel \
  sqlite3.O0.ll -o /dev/null 2> err

where sqlite3.O0.ll is non-optimized IR produced from
sqlite-amalgamation (http://sqlite.org/download.html), which is entire
SQLite3 implementation in a single C-file.

Benchmarked on 4-cores / 8 threads PCI-E SSD iMac running macOS

Reviewers: dexonsmith, bkramer, void, chandlerc, aditya_nandakumar, dsanders, qcolombet, 

Reviewed By: bogner

Subscribers: thegameg, llvm-commits

Differential Revision: https://reviews.llvm.org/D44132

llvm-svn: 328246

0 files changed, 0 insertions, 0 deletions