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llvm-project/llvm/test/CodeGen/SystemZ/Large/branch-range-07.py

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[SystemZ] Use BRCT and BRCTG to eliminate add-&-compare sequences This patch just uses a peephole test for "add; compare; branch" sequences within a single block. The IR optimizers already convert loops to decrement-and-branch-on-nonzero form in some cases, so even this simplistic test triggers many times during a clang bootstrap and projects/test-suite run. It looks like there are still cases where we need to more strongly prefer branches on nonzero though. E.g. I saw a case where a loop that started out with a check for 0 ended up with a check for -1. I'll try to look at that sometime. I ended up adding the Reference class because MachineInstr::readsRegister() doesn't check for subregisters (by design, as far as I could tell). llvm-svn: 187723
2013-08-05 19:23:46 +08:00
# Test 32-bit BRANCH RELATIVE ON COUNT in cases where some branches are out
# of range.
# RUN: python %s | llc -mtriple=s390x-linux-gnu | FileCheck %s
# Construct:
#
# loopN:
# load of countN
# ...
# loop0:
# 0xffd8 bytes, from MVIY instructions
# conditional branch to main
# after0:
# ...
# decrement of countN
# conditional branch to loopN
# afterN:
#
# Each load occupies 4 bytes. Each decrement and branch occupies 4
# bytes if BRCT can be used, otherwise it occupies 10 bytes (AHI + BRCL).
# This means that loop 6 contains 5 * 4 + 0xffd8 + 5 * 4 == 0x10000 bytes
# and is therefore (just) in range. Loop 7 is out of range.
#
# CHECK: brct {{%r[0-9]+}}
# CHECK: brct {{%r[0-9]+}}
# CHECK: brct {{%r[0-9]+}}
# CHECK: brct {{%r[0-9]+}}
# CHECK: brct {{%r[0-9]+}}
# CHECK: brct {{%r[0-9]+}}
# CHECK: ahi {{%r[0-9]+}}, -1
# CHECK: jglh
# CHECK: ahi {{%r[0-9]+}}, -1
# CHECK: jglh
branch_blocks = 8
main_size = 0xffd8
print 'define void @f1(i8 *%base, i32 *%counts) {'
print 'entry:'
for i in xrange(branch_blocks - 1, -1, -1):
Update SystemZ/Large test generators to handle new gep IR syntax llvm-svn: 230810
2015-02-28 07:29:39 +08:00
print ' %%countptr%d = getelementptr i32, i32 *%%counts, i64 %d' % (i, i)
Update SystemZ/Large test generators to handle new load IR syntax llvm-svn: 230809
2015-02-28 07:29:33 +08:00
print ' %%initcount%d = load i32 , i32 *%%countptr%d' % (i, i)
[SystemZ] Use BRCT and BRCTG to eliminate add-&-compare sequences This patch just uses a peephole test for "add; compare; branch" sequences within a single block. The IR optimizers already convert loops to decrement-and-branch-on-nonzero form in some cases, so even this simplistic test triggers many times during a clang bootstrap and projects/test-suite run. It looks like there are still cases where we need to more strongly prefer branches on nonzero though. E.g. I saw a case where a loop that started out with a check for 0 ended up with a check for -1. I'll try to look at that sometime. I ended up adding the Reference class because MachineInstr::readsRegister() doesn't check for subregisters (by design, as far as I could tell). llvm-svn: 187723
2013-08-05 19:23:46 +08:00
print ' br label %%loop%d' % i
print 'loop%d:' % i
block1 = 'entry' if i == branch_blocks - 1 else 'loop%d' % (i + 1)
block2 = 'loop0' if i == 0 else 'after%d' % (i - 1)
print (' %%count%d = phi i32 [ %%initcount%d, %%%s ],'
' [ %%nextcount%d, %%%s ]' % (i, i, block1, i, block2))
a, b = 1, 1
for i in xrange(0, main_size, 6):
a, b = b, a + b
offset = 4096 + b % 500000
value = a % 256
Update SystemZ/Large test generators to handle new gep IR syntax llvm-svn: 230810
2015-02-28 07:29:39 +08:00
print ' %%ptr%d = getelementptr i8, i8 *%%base, i64 %d' % (i, offset)
[SystemZ] Use BRCT and BRCTG to eliminate add-&-compare sequences This patch just uses a peephole test for "add; compare; branch" sequences within a single block. The IR optimizers already convert loops to decrement-and-branch-on-nonzero form in some cases, so even this simplistic test triggers many times during a clang bootstrap and projects/test-suite run. It looks like there are still cases where we need to more strongly prefer branches on nonzero though. E.g. I saw a case where a loop that started out with a check for 0 ended up with a check for -1. I'll try to look at that sometime. I ended up adding the Reference class because MachineInstr::readsRegister() doesn't check for subregisters (by design, as far as I could tell). llvm-svn: 187723
2013-08-05 19:23:46 +08:00
print ' store volatile i8 %d, i8 *%%ptr%d' % (value, i)
for i in xrange(branch_blocks):
print ' %%nextcount%d = add i32 %%count%d, -1' % (i, i)
print ' %%test%d = icmp ne i32 %%nextcount%d, 0' % (i, i)
print ' br i1 %%test%d, label %%loop%d, label %%after%d' % (i, i, i)
print ''
print 'after%d:' % i
print ' ret void'
print '}'