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[SystemZ] Use MVC to spill loads and stores

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Try to use MVC when spilling the destination of a simple load or the source
of a simple store.  As explained in the comment, this doesn't yet handle
the case where the load or store location is also a frame index, since
that could lead to two simultaneous scavenger spills, something the
backend can't handle yet.  spill-02.py tests that this restriction kicks in,
but unfortunately I've not yet found a case that would fail without it.
The volatile trick I used for other scavenger tests doesn't work here
because we can't use MVC for volatile accesses anyway.

I'm planning on relaxing the restriction later, hopefully with a test
that does trigger the problem...

Tests @f8 and @f9 also showed that L(G)RL and ST(G)RL were wrongly
classified as SimpleBDX{Load,Store}.  It wouldn't be easy to test for
that bug separately, which is why I didn't split out the fix as a
separate patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185434 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Sandiford
2013-07-02 15:28:56 +00:00
parent 9188443a2d
commit 1ce4894a3f
6 changed files with 582 additions and 13 deletions
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40
test/CodeGen/SystemZ/Large/spill-01.py Normal file
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# Test cases where MVC is used for spill slots that end up being out of range.
# RUN: python %s | llc -mtriple=s390x-linux-gnu | FileCheck %s
# There are 8 usable call-saved GPRs, two of which are needed for the base
# registers. The first 160 bytes of the frame are needed for the ABI
# call frame, and a further 8 bytes are needed for the emergency spill slot.
# That means we will have at least one out-of-range slot if:
#
# count == (4096 - 168) / 8 + 6 + 1 == 498
#
# Add in some extra room and check both %r15+4096 (the first out-of-range slot)
# and %r15+4104.
#
# CHECK: f1:
# CHECK: lay [[REG:%r[0-5]]], 4096(%r15)
# CHECK: mvc 0(8,[[REG]]), {{[0-9]+}}({{%r[0-9]+}})
# CHECK: brasl %r14, foo@PLT
# CHECK: lay [[REG:%r[0-5]]], 4096(%r15)
# CHECK: mvc {{[0-9]+}}(8,{{%r[0-9]+}}), 8([[REG]])
# CHECK: br %r14
count = 500
print 'declare void @foo()'
print ''
print 'define void @f1(i64 *%base0, i64 *%base1) {'
for i in range(count):
print ' %%ptr%d = getelementptr i64 *%%base%d, i64 %d' % (i, i % 2, i / 2)
print ' %%val%d = load i64 *%%ptr%d' % (i, i)
print ''
print ' call void @foo()'
print ''
for i in range(count):
print ' store i64 %%val%d, i64 *%%ptr%d' % (i, i)
print ''
print ' ret void'
print '}'