https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66049
Bug ID: 66049
Summary: Few AArch64 extend and add with shift tests generates
sub optimal code with trunk gcc 6.0.
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: vekumar at gcc dot gnu.org
Target Milestone: ---
After preventing conversion of shift to mults in combiner
https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=222874
few Aarch64 target tests generates suboptimal code.
Tests that now fail, but worked before:
---------------------------------------
gcc.target/aarch64/adds1.c scan-assembler adds\tw[0-9]+, w[0-9]+, w[0-9]+, lsl
3
gcc.target/aarch64/adds1.c scan-assembler adds\tx[0-9]+, x[0-9]+, x[0-9]+, lsl
3
gcc.target/aarch64/adds3.c scan-assembler-times adds\tx[0-9]+, x[0-9]+,
x[0-9]+,
sxtw 2
gcc.target/aarch64/extend.c scan-assembler add\tw[0-9]+,.*uxth #?1
gcc.target/aarch64/extend.c scan-assembler add\tx[0-9]+,.*uxtw #?3
gcc.target/aarch64/extend.c scan-assembler sub\tw[0-9]+,.*uxth #?1
gcc.target/aarch64/extend.c scan-assembler sub\tx[0-9]+,.*uxth #?1
gcc.target/aarch64/extend.c scan-assembler sub\tx[0-9]+,.*uxtw #?3
gcc.target/aarch64/subs1.c scan-assembler subs\tw[0-9]+, w[0-9]+, w[0-9]+, lsl
3
gcc.target/aarch64/subs1.c scan-assembler subs\tx[0-9]+, x[0-9]+, x[0-9]+, lsl
3
gcc.target/aarch64/subs3.c scan-assembler-times subs\tx[0-9]+, x[0-9]+,
x[0-9]+,
sxtw 2
Sample Test case
----------------
unsigned long long
adddi_uxtw (unsigned long long a, unsigned int i)
{
/* { dg-final { scan-assembler "add\tx\[0-9\]+,.*uxtw #?3" } } */
return a + ((unsigned long long)i << 3);
}
Before
add x0, x0, x1, uxtw 3
Now
ubfiz x1, x1, 3, 32
add x0, x1, x0
