ccs6.1.2 debug模式，可以编译重复定义了全局变量的代码？？

默认debug模式是没有加优化选项的，没有从工程级来优化，编译器只对单个文件进行编译，其它文件的情况是不关心的。而release mode是从整个工程进行优化的。

• --opt_level=0 or -O0
– Performs control-flow-graph simplification
– Allocates variables to registers
– Performs loop rotation
– Eliminates unused code
– Simplifies expressions and statements
– Expands calls to functions declared inline
• --opt_level=1 or -O1
Performs all --opt_level=0 (-O0) optimizations, plus:
– Performs local copy/constant propagation
– Removes unused assignments
– Eliminates local common expressions
• --opt_level=2 or -O2
Performs all --opt_level=1 (-O1) optimizations, plus:
– Performs software pipelining (see Section 3.2)
– Performs loop optimizations
– Eliminates global common subexpressions
– Eliminates global unused assignments
– Converts array references in loops to incremented pointer form
– Performs loop unrolling
The optimizer uses --opt_level=2 (-O2) as the default if you use --opt_level (-O) without an optimization
level.
• --opt_level=3 or -O3
Performs all --opt_level=2 (-O2) optimizations, plus:
– Removes all functions that are never called
– Simplifies functions with return values that are never used
– Inlines calls to small functions
– Reorders function declarations; the called functions attributes are known when the caller is
optimized
– Propagates arguments into function bodies when all calls pass the same value in the same
argument position
– Identifies file-level variable characteristics
If you use --opt_level=3 (-O3), see Section 3.6 and Section 3.7 for more information.