[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 --- Comment #6 from Segher Boessenkool --- "All"... not the non-finite denormals ;-)
[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 Michael Meissner changed: What|Removed |Added Ever confirmed|0 |1 Last reconfirmed||2024-03-27 Status|UNCONFIRMED |NEW --- Comment #5 from Michael Meissner --- Power10 can now load all SFmode constants and many DFmode constants via the XXSPLTIDP instructions. As time goes by, I would imagine doing this optimization for power8 and power9 machines becomes less important.
[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 Jens Seifert changed: What|Removed |Added CC||jens.seifert at de dot ibm.com --- Comment #4 from Jens Seifert --- values -16.0..+15.0. vspltisw 0, xvcvsxwdp 32,32 values -16.0f..+15.0f vspltisw 0, xvcvsxwsp 32,32 -0.0 / 0x8000 xxlxor 32,32,32 xvnabsdp 32,32 or xvnegdp 32,32 -0.0f / 0x8000 xxlxor 32,32,32 xvnabssp 32,32 or xvnegsp 32,32 0x7FFF vspltisw 0,-1 xvabsdp 32,32 0x7FFF vspltisw 0,-1 xvabssp 32,32
[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 Bill Schmidt changed: What|Removed |Added CC||jens.seifert at de dot ibm.com --- Comment #3 from Bill Schmidt --- *** Bug 93128 has been marked as a duplicate of this bug. ***
[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 --- Comment #2 from Peter Bergner --- Can powers of 2 values be generated with a splat followed by a shift?
[Bug target/70928] Load simple float constants via VSX operations on PowerPC
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70928 --- Comment #1 from Bill Schmidt --- Short sequences for the rest of -32 to 31 are possible also. The splats can be done as follows. x even, x in [-32,-18] U [16,30]: vspltis[bhw] t, x vaddu[bhw]m y, t, t x odd, x in [17,31]: vspltis[bhw] t, x-16 vspltis[bhw] u, -16 vsubu[bhw]m y, t, u x odd, x in [-31,-17]: vspltisw t, x+16 vspltisw u, -16 vadduwm y, t, u These can then again be unpacked and converted to floating point. This may or may not be preferable to a load, as the dependency chains start to get a bit long.
