Some of these tests did not specify a cpu but were also sensitive to
instruction scheduling and/or register assignment choices. A few others
similarly-sensitive tests specified a cpu (often the POWER7), and while the P7
currently uses the default model for PPC64, this will soon change. For those
tests which should not really be cpu-dependent anyway, the cpu is set to the
generic 'ppc64'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195977 91177308-0d34-0410-b5e6-96231b3b80d8
This is a preliminary patch for fast instruction selection on
PowerPC. Code generation can differ between DAG isel and fast isel.
Existing tests that specify -O0 were written to expect DAG isel. Make
this explicit by adding -fast-isel=false to the tests.
In some cases specifying -fast-isel=false produces different code even
when there isn't a fast instruction selector specified. This is
because TM.Options.EnableFastISel = 1 at -O0 whether or not a FastISel
object exists. Thus disabling fast isel can actually produce less
conservative code. Because of this, some of the expected code
generation in the -O0 tests needs to be adjusted.
In particular, handling of function arguments is less conservative
with -fast-isel=false (see isOnlyUsedInEntryBlock() in
SelectionDAGBuilder.cpp). This results in fewer stack accesses and,
in some cases, reduced stack size as uselessly loaded values are no
longer stored back to spill locations in the stack.
No functional change with this patch; test case adjustments only.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183939 91177308-0d34-0410-b5e6-96231b3b80d8
Some implementation detail in the forgotten past required the link
register to be placed in the GPRC and G8RC register classes. This is
just wrong on the face of it, and causes several extra intersection
register classes to be generated. I found this was having evil
effects on instruction scheduling, by causing the wrong register class
to be consulted for register pressure decisions.
No code generation changes are expected, other than some minor changes
in instruction order. Seven tests in the test bucket required minor
tweaks to adjust to the new normal.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178114 91177308-0d34-0410-b5e6-96231b3b80d8
structs having size 3, 5, 6, or 7. Such a struct must be passed and received
as right-justified within its register or memory slot. The problem is only
present for structs that are passed in registers.
Previously, as part of a patch handling all structs of size less than 8, I
added logic to rotate the incoming register so that the struct was left-
justified prior to storing the whole register. This was incorrect because
the address of the parameter had already been adjusted earlier to point to
the right-adjusted value in the storage slot. Essentially I had accidentally
accounted for the right-adjustment twice.
In this patch, I removed the incorrect logic and reorganized the code to make
the flow clearer.
The removal of the rotates changes the expected code generation, so test case
structsinregs.ll has been modified to reflect this. I also added a new test
case, jaggedstructs.ll, to demonstrate that structs of these sizes can now
be properly received and passed.
I've built and tested the code on powerpc64-unknown-linux-gnu with no new
regressions. I also ran the GCC compatibility test suite and verified that
earlier problems with these structs are now resolved, with no new regressions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166680 91177308-0d34-0410-b5e6-96231b3b80d8
