https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89434
Tamar Christina <tnfchris at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tnfchris at gcc dot gnu.org
--- Comment #8 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
This is causing a glibc build failure on arm-none-Linux-gnueabihf, for some
reason I can only reproduce it native but not cross. Don't exactly know why...
configured with
```
--enable-languages=c,c++,fortran --target=arm-none-linux-gnueabihf
--build=arm-none-linux-gnueabihf --host=arm-none-linux-gnueabihf
--with-arch=armv7-a --with-fpu=neon --with-float=hard --with-mode=thumb
```
repro case
```
long long a;
void f () {
if (a >= 9223372036854775807 - 1 + 400)
for (;;)
;
}
```
compiled with
```
-c -O2 -Wno-maybe-uninitialized
```
Which gets combined by combine into
```
Trying 8 -> 10:
8: r112:DI=0x800000000000018e
10: {cc:CC_NCV=cmp(r113:DI,r112:DI);clobber scratch;}
REG_DEAD r113:DI
REG_DEAD r112:DI
REG_EQUAL cmp(r113:DI,0x800000000000018e)
Successfully matched this instruction:
(parallel [
(set (reg:CC_NCV 100 cc)
(compare:CC_NCV (reg:DI 113 [ aD.5557 ])
(const_int -9223372036854775410 [0x800000000000018e])))
(clobber (scratch:SI))
])
allowing combination of insns 8 and 10
```
and then later is split into
```
(insn 51 50 11 2 (parallel [
(set (reg:CC 100 cc)
(compare:CC (reg:SI 3 r3 [ aD.5557+4 ])
(const_int -2147483648 [0xffffffff80000000])))
(set (reg:SI 3 r3 [114])
(minus:SI (plus:SI (reg:SI 3 r3 [ aD.5557+4 ])
(const_int -2147483648 [0xffffffff80000000]))
(ltu:SI (reg:CC_C 100 cc)
(const_int 0 [0]))))
]) "zic.i":4:6 -1
(nil))
```
Which matches no instruction and so ICEs. On a cross build this seems to get
split into
```
(insn 51 50 11 2 (parallel [
(set (reg:CC 100 cc)
(compare:CC (reg:SI 3 r3 [ aD.5557+4 ])
(const_int 2147483647 [0x7fffffff])))
(set (reg:SI 3 r3 [114])
(minus:SI (plus:SI (reg:SI 3 r3 [ aD.5557+4 ])
(const_int 2147483647 [0x7fffffff]))
(ltu:SI (reg:CC_C 100 cc)
(const_int 0 [0]))))
]) "zin.i":4:6 32 {*subsi3_carryin_compare_const}
(nil))
```
So the constants seem to be different.
