On 06/16/2010 05:40 PM, Pavel Pavlov wrote: >> -----Original Message----- >> From: Andrew Haley [mailto:aph@xxxxxxxxxx] >> On 06/16/2010 05:11 PM, Pavel Pavlov wrote: >>>> -----Original Message----- >>>> On 06/16/2010 01:15 PM, Andrew Haley wrote: >>>>> On 06/16/2010 11:23 AM, Pavel Pavlov wrote: >>> ... >>>> inline uint64_t smlalbb(uint64_t acc, unsigned int lo, unsigned int hi) { >>>> union >>>> { >>>> uint64_t ll; >>>> struct >>>> { >>>> unsigned int l; >>>> unsigned int h; >>>> } s; >>>> } retval; >>>> >>>> retval.ll = acc; >>>> >>>> __asm__("smlalbb %0, %1, %2, %3" >>>> : "+r"(retval.s.l), "+r"(retval.s.h) >>>> : "r"(lo), "r"(hi)); >>>> >>>> return retval.ll; >>>> } >>>> >>> >>> [Pavel Pavlov] >>> Later on I found out that I had to use +r constraint, but then, when I use that >> function for example like that: >>> int64_t rsmlalbb64(int64_t i, int x, int y) { >>> return smlalbb64(i, x, y); >>> } >>> >>> Gcc generates this asm: >>> <rsmlalbb64>: >>> push {r4, r5} >>> mov r4, r0 >>> mov ip, r1 >>> smlalbb r4, ip, r2, r3 >>> mov r5, ip >>> mov r0, r4 >>> mov r1, ip >>> pop {r4, r5} >>> bx lr >>> >>> It's bizarre what gcc is doing in that function, I understand if it >>> can't optimize and correctly use r0 and r1 directly, but from that >>> listing it looks as if gcc got drunk and decided to touch r5 for >>> absolutely no reason! >>> >>> the expected out should have been like that: >>> <rsmlalbb64>: >>> smlalbb r0, r1, r2, r3 >>> bx lr >>> >>> I'm using cegcc 4.1.0 and I compile with >>> arm-mingw32ce-g++ -O3 -mcpu=arm1136j-s -c ARM_TEST.cpp -o >>> arm-mingw32ce-g++ ARM_TEST_GCC.obj >>> >>> Is there a way to access individual parts of that 64-bit input integer >>> or, is there a way to specify that two 32-bit integers should be >>> treated as a Hi:Lo parts of 64 bit variable. It's commonly done with a >>> temporary, but the result is that gcc generates to much junk. >> >> Why don't you just use the function I sent above? It generates >> >> smlalbb: >> smlalbb r0, r1, r2, r3 >> mov pc, lr >> >> smlalXX64: >> smlalbb r0, r1, r2, r3 >> smlalbt r0, r1, r2, r3 >> smlaltb r0, r1, r2, r3 >> smlaltt r0, r1, r2, r3 >> mov pc, lr >> > > [Pavel Pavlov] > What's your gcc -v? The output I posted comes from your function. 4.3.0 Perhaps your compiler options were wrong? Dunno. Andrew.
