> -----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.
