Deng Shi wrote:
-----Original Message-----
From: Deng Shi
Sent: 2006年7月13日 10:37
To: 'gnu-help@xxxxxxx'
Subject: Inconsistent floating point result when using G++ 3.3.6 with option -O0 or -O1 separately
hi expert,
I found our application tool gave the inconsistent floating point result when using different optimization level -O0 or -O1.
Even if I used -O1 plus all the disabling options which includes in -O1, like -O1 -fno-merge-all-constants -fno-zero-initialized-in-bss -fno-function-cse -fno-keep-static-consts -fno-omit-frame-pointer -fno-merge-constants -fno-loop-optimize -fno-cprop-registers -fno-if-conversion -fno-if-conversion2 -fno-delayed-branch -fno-guess-branch-probability -fno-defer-pop -fno-crossjumping -fno-thread-jumps " which command line setting should be equal to -O0, but I still didn't get the consistent result.
I wonder whether there is any additional optimization enabled by -O1 for C++ language which is not documented in GCC manual?
If you're generating x87 code (the default for ia32), -ffloat-store
would be among the first options normally tried to remove extra
precision. How are we to know what target you have, and which options
you used?
