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Re: [PATCH][ARM] optimizing _muldi3 for Thumb

Doug Kwan (éæå) wrote: 
The compiler already uses very efficient code to do 64-bit
multiplication in ARM mode.  In the THUMB mode, the same code cannot
be generated because the required instructions are not available. So
64-bit multiplication in THUMB is done by calling libgcc, which
implements 64-bit multiplication using 32-bit operations in C. The
code is inherently not very efficient and never uses the ARM
multiplication instruction because it is compiled for THUMB.

Are you saying that the libgcc ASM implementation that you've written always runs in ARM mode, then? That's probably not valid on a Thumb-only CPU, then. Does your patch handle that?

--
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713

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