This is now backported to GCC 10.
Andrew
On 11/09/2020 11:17, Andrew Stubbs wrote:
This patch fixes an execution failure in which the compiler would
corrupt TImode values due to missed early clobber problems with
partially overlapping register allocations. In fact, adding early
clobber constraints does not fix the issue because IRA doesn't check
that for move instructions properly in all circumstances anyway (the
constraint causes an ICE in postreload).
This patch fixes the problem by ensuring that TImode values are always
aligned to 4-register boundaries, meaning that inputs and outputs will
either overlap completely, or not at all, neither of which have
early-clobber issues.
This is an artificial restriction the hardware not present in hardware ,
but it is the same solution we use for DImode values where we had a lot
of the same problems.
With the patch I see the following new test passes:
PASS: gfortran.dg/PR95331.f90 -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions execution test
PASS: gfortran.dg/PR95331.f90 -O3 -g execution test
PASS: gfortran.dg/gamma_5.f90 -O0 execution test
PASS: gfortran.dg/gamma_5.f90 -O1 execution test
PASS: gfortran.dg/gamma_5.f90 -O2 execution test
PASS: gfortran.dg/gamma_5.f90 -O3 -fomit-frame-pointer -funroll-loops
-fpeel-loops -ftracer -finline-functions execution test
PASS: gfortran.dg/gamma_5.f90 -O3 -g execution test
PASS: gfortran.dg/gamma_5.f90 -Os execution test
PASS: gfortran.dg/intrinsic_pack_1.f90 -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions execution test
PASS: gfortran.dg/intrinsic_pack_1.f90 -O3 -g execution test
PASS: gfortran.dg/optional_absent_5.f90 -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions execution test
PASS: gfortran.dg/optional_absent_5.f90 -O3 -g execution test
Andrew
