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author | Jeff Law <jlaw@ventanamicro.com> | 2024-08-17 10:30:48 -0600 |
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committer | Jeff Law <jlaw@ventanamicro.com> | 2024-08-17 10:30:48 -0600 |
commit | abfc140579682598cd178eb9d0b0160bbfafc633 (patch) | |
tree | 031cb22c7fdd669dd2c08738203df9ca706e0ef9 /libgo/config.h.in | |
parent | 6d734ba485547329599f12bea63842a4fba8d72c (diff) | |
download | gcc-master.zip gcc-master.tar.gz gcc-master.tar.bz2 |
The recent if-conversion changes tripped a failure on the v850 port.
The core underlying issue is that while the if-conversion code tries to do the
right thing with noce_can_force_operand to determine if it can force an
arbitrary operand into a register, it's not really a sufficient check.
Essentially for arithmetic codes, it checks the operands. If the operands are
force-able and there's a code_to_optab mapping, then it returns true.
code_to_optab doesn't actually check anything other than the existence of a
mapping in the target. If the target pattern has restrictions enforced by the
condition or it's an expander that is allowed to FAIL, then
noce_can_force_operand to be true, even though we may not be able to directly
force the operand into a register.
This came up on the v850 when we had an operand that was a rotate by a constant
number of bits (I don't remember the count, all that's important about it was
the count was not 8 or 16).
The v850 port has this define_expand:
> (define_expand "rotlsi3"
> [(parallel [(set (match_operand:SI 0 "register_operand" "")
> (rotate:SI (match_operand:SI 1 "register_operand" "")
> (match_operand:SI 2 "const_int_operand" "")))
> (clobber (reg:CC CC_REGNUM))])]
> "(TARGET_V850E_UP)"
> {
> if (INTVAL (operands[2]) != 16)
> FAIL;
> })
So the only rotate count allowed is 16 (there's a similar HI rotate with a count of 8). AFAICT the rotate patterns are allowed to FAIL. So naturally the expander fails and we get a testsuite regression:
> Tests that now fail, but worked before (4 tests):
>
> v850-sim/-mgcc-abi/-msoft-float/-mv850e3v5: gcc: gcc.c-torture/execute/20100805-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess errors)
> v850-sim/-mgcc-abi/-msoft-float/-mv850e3v5: gcc: gcc.c-torture/execute/20100805-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess errors)
> v850-sim/-msoft-float/-mv850e3v5: gcc: gcc.c-torture/execute/20100805-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess errors)
> v850-sim/-mv850e3v5: gcc: gcc.c-torture/execute/20100805-1.c -O3 -fomit-frame-pointer -funroll-loops -fpeel-loops -ftracer -finline-functions (test for excess errors)
This patch works around the problem by allowing the rotates in additional
cases, particularly for the V850E3V5+ variants which have a general rotate
capability. But let's be clear, this is just a workaround and I expect we're
going to have to revisit the code to test if an operand can be forced into a
register.
gcc/
* config/v850/v850.md (rotlsi3): Allow more cases for V850E3V5+.
Diffstat (limited to 'libgo/config.h.in')
0 files changed, 0 insertions, 0 deletions