[llvm-dev] Why LLVM cannot optimize this?

[zet via llvm-dev]

test.c :
-----------------------------------------------------------------------
int foo(int a)
{
  int zero = 0;
  for (int i = 0; i < 10000; i++)
    zero *= a;
  return zero;
}
-------------------------------------------------------------------------

run clang : clang -O2 -S test.c -o test.s

My clang version is 3.7.1.
We will get a horrible assembly output.

Why constant propagation and other optimization skills can not find out
that variable zero is initialized 0, and the only statement in for loop
(i.e. zero *= a) always get a 0?

I can read the clang/llvm source, Please tell me more details.

THX


-- 
业精于勤,荒于嬉..
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