ECE540S Optimizing Compilers

1
ECE540SOptimizing Compilers

• http//www.eecg.toronto.edu/voss/ece540/
• Using Simple SUIF

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The SUIF Compiler

• A compiler infrastructure from Stanford
  University (Stanford University Intermediate
  Format).
• Research Compiler not production quality slow
  but modular.
• Optimizations are implemented in passes that
  communicate via binary files.
• Implemented in C.
• Optimizations for uni-processor (scalar
  optimizations) and for parallel processors.
• Simple-SUIF is a C implementation of SUIF that is
  intended for scalar optimizations, and is
  simplified for educational use.

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Simple-SUIF

• Few instruction format
• op
• op dest src
• op dest src1 src2
• jmp label
• See The Simple-SUIF Compiler Guide and
  /cad1/ece540/suif/include/simple.h for details on
  instructions and their formats.

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Simple-SUIF

• Operands
• registers (most instructions).
• variables (loads and stores).
• immediate values (ldc instruction).
• procedures/functions (call instruction).
• labels (jump and branch instructions).
• Types
• used in instructions to indicate type of result.
• Registers
• temporary
• registers with only one assignment and one use,
  both within a basic block.
• temporary variables that do not need global
  optimization typically intermediate values.
• pseudo temporary variables that need global
  optimization.
• machine actual machine register (only used in
  register allocation).

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Simple-SUIF Instructions
ldc (s.32) t4 0 cpy (s.32) r2
t4 ldc (s.32) t5 10 cpy
(s.32) r3 t5 ldc (s.32) t6 0
sl (s.32) t7 t6, r3 bfls
t7, L3 ldc (s.32) t8 0
cpy (s.32) r1 t8 L4 ldc
(s.32) t9 1 add (s.32) t10 r2,
t9 cpy (s.32) r2 t10 L1
ldc (s.32) t11 1 add (s.32) t12
r1, t11 cpy (s.32) r1 t12
sle (s.32) t13 r3, r1 bfls
t13, L4 L2 jmp
__done5 L3 ldc (s.32) t14 0
cpy (s.32) r1 t14 __done5
main() int i,c,n c 0 n 10
for (i0 i lt n i) c c 1

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Writing a Compiler Pass

• You are given
• Simple-SUIF data structures and library function
  interfaces. (/cad1/ece540/suif/include/simple.h)
• main.cc (a C file). It performs the following
  for each procedure in ltfilegt.tmp
• read the procedure and builds Simple-SUIF data
  structures (front-end).
• call do_procedure(simple_instr inlist, char
  proc_name).
• write modified structure to output file.
• You must write the do_procedure function to
  analyze and modify Simple-SUIF data structures.
• Example printsimple.c a pass that prints the
  instructions in a ltfilegt.tmp.

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Writing a Compiler Pass (continued)
simple_instr do_procedure (simple_instr
inlist, char proc_name) simple_instr
i printf("\nProcedure s\n",
proc_name) i inlist while (i)
fprint_instr(stdout, i) i i-gtnext
return inlist
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Writing a Compiler Pass (continued)

• Do this on a ugsparc.eecg machine

mkdir -p /ece540/printsimple cd
/ece540/printsimple cp /cad1/ece540/printsimple
/ . ls Makefile doproc.c main.cc print.c
print.h make make depend g -c -g
-I/cad1/ece540/suif/include main.cc gcc -c -g
-I/cad1/ece540/suif/include doproc.c gcc -c -g
-I/cad1/ece540/suif/include print.c g -o
printsimple -g -I /cad1/ece540/suif/include
main.o doproc.o print.o -L/cad1/ece540/suif/SPARC/
lib -lsimple -lsuif
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Writing a Compiler Pass (continued)
cat test.c int main() return 0 ssfe
test ls test. test.c test.tmp printsimple
test.tmp test.spx Procedure main ldc (s.32)
t1 0 ret ssbe test ls test. test.c
test.s test.tmp test.spx rlogin skule.ecf cd
/ece540/printsimple ftp ugsparc10.eecg gt get
test.s gt quit masm test ./test
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Representation of Sets

• Sets are typically represented as bit-vectors
  one bit for each object in the set.
• A 1-bit indicates presence in the set a 0-bit
  indicates absence from the set.
• Set union is implemented using bit-or operations.
• Set intersection is implemented using bit-and
  operations.
• Set difference A-B is implemented as A and (not
  B).
• Code that implements sets is provided to you. See
  the files bitvector. in /cad1/ece540/hw/hw1/src/
  .