https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83565
--- Comment #2 from Sergei Trofimovich <slyfox at inbox dot ru> ---
Where the change happens (today's gcc master):
$./bin/ia64-unknown-linux-gnu-gcc -O1 -S a.c -fdump-rtl-all
$ fgrep -A3 zero_extract a.c.*
zero_extract extracted 31 bits at offset 1:
a.c.262r.init-regs: (zero_extract:DI (reg:DI 358)
a.c.262r.init-regs- (const_int 31 [0x1f])
a.c.262r.init-regs- (const_int 1 [0x1]))) "a.c":28 159 {extzv}
a.c.262r.init-regs- (expr_list:REG_DEAD (reg:DI 358)
a.c.264r.combine:insn_cost 4 for 23: r359:DI=zero_extract(r358:DI,0x1f,0x1)
a.c.264r.combine- REG_DEAD r358:DI
a.c.264r.combine-insn_cost 4 for 24: r356:SI#0=r359:DI
a.c.264r.combine- REG_DEAD r359:DI
a.c.264r.combine:modifying insn i3 29: r8:DI=zero_extract(r358:DI,0x20,0x1)
a.c.264r.combine- REG_DEAD r358:DI
a.c.264r.combine-deferring rescan insn with uid = 29.
a.c.264r.combine-starting the processing of deferred insns
zero_extract extracts 32 bits at offset 1:
a.c.264r.combine: (zero_extract:DI (reg:DI 358)
a.c.264r.combine- (const_int 32 [0x20])
a.c.264r.combine- (const_int 1 [0x1]))) "a.c":33 159 {extzv}
a.c.264r.combine- (expr_list:REG_DEAD (reg:DI 358)
