https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90822
Bug ID: 90822
Summary: Remove PowerPC lfiwax and lfiwzx patterns
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: meissner at gcc dot gnu.org
Target Milestone: ---
When I first added the patterns for LFIWAX and LFIWZX instructions (back in
2010), I wanted to add support for these instructions, but at the time we
didn't have automatic sign/zero extension from SImode to DImode, and I was
worried about allowing SImode in the floating point and vector registers.
The initial pattern that is generated is:
(insn 6 5 7 (parallel [
(set (reg:DF 120)
(float:DF (mem:SI (reg/v/f:DI 119 [ p ]) [1 *p_3(D)+0 S4
A32])))
(clobber (scratch:DI))
]) "foo50.c":1:30 -1
(nil))
After the split1 pass we generate:
(insn 15 6 16 2 (set (reg:DI 122)
(unspec:DI [
(mem:SI (reg:DI 121) [1 *p_3(D)+0 S4 A32])
] UNSPEC_LFIWAX)) "foo50.c":1:1 -1
(nil))
(insn 16 15 12 2 (set (reg/i:DF 33 1)
(float:DF (reg:DI 122))) "foo50.c":1:1 -1
(nil))
Instead, we should generate in the split1 pass:
(insn 15 6 16 2 (set (reg:DI 122)
(sign_extend:DI (mem:SI (reg:DI 121))))
(insn 16 15 12 2 (set (reg/i:DF 33 1)
(float:DF (reg:DI 122))) "foo50.c":1:1 -1
(nil))
And delete the lfiwax (and similar lfiwzx) patterns.
Obviously, we want to make sure we don't affect code generation for the power7
targets (for lfiwax/lfiwzx) and power6 targets (for just lfiwax).
