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llvm-mirror/test/CodeGen/SPARC/64cond.ll
Andrew Trick b401fd4c9e Allocate local registers in order for optimal coloring.
Also avoid locals evicting locals just because they want a cheaper register.

Problem: MI Sched knows exactly how many registers we have and assumes
they can be colored. In cases where we have large blocks, usually from
unrolled loops, greedy coloring fails. This is a source of
"regressions" from the MI Scheduler on x86. I noticed this issue on
x86 where we have long chains of two-address defs in the same live
range. It's easy to see this in matrix multiplication benchmarks like
IRSmk and even the unit test misched-matmul.ll.

A fundamental difference between the LLVM register allocator and
conventional graph coloring is that in our model a live range can't
discover its neighbors, it can only verify its neighbors. That's why
we initially went for greedy coloring and added eviction to deal with
the hard cases. However, for singly defined and two-address live
ranges, we can optimally color without visiting neighbors simply by
processing the live ranges in instruction order.

Other beneficial side effects:

It is much easier to understand and debug regalloc for large blocks
when the live ranges are allocated in order. Yes, global allocation is
still very confusing, but it's nice to be able to comprehend what
happened locally.

Heuristics could be added to bias register assignment based on
instruction locality (think late register pairing, banks...).

Intuituvely this will make some test cases that are on the threshold
of register pressure more stable.

llvm-svn: 187139
2013-07-25 18:35:14 +00:00

112 lines
2.5 KiB
LLVM

; RUN: llc < %s -mtriple=sparc64-pc-openbsd -disable-sparc-leaf-proc | FileCheck %s
; Testing 64-bit conditionals. The sparc64 triple is an alias for sparcv9.
; CHECK: cmpri
; CHECK: cmp %i1, 1
; CHECK: be %xcc,
define void @cmpri(i64* %p, i64 %x) {
entry:
%tobool = icmp eq i64 %x, 1
br i1 %tobool, label %if.end, label %if.then
if.then:
store i64 %x, i64* %p, align 8
br label %if.end
if.end:
ret void
}
; CHECK: cmprr
; CHECK: cmp %i1, %i2
; CHECK: bgu %xcc,
define void @cmprr(i64* %p, i64 %x, i64 %y) {
entry:
%tobool = icmp ugt i64 %x, %y
br i1 %tobool, label %if.end, label %if.then
if.then:
store i64 %x, i64* %p, align 8
br label %if.end
if.end:
ret void
}
; CHECK: selecti32_xcc
; CHECK: cmp %i0, %i1
; CHECK: movg %xcc, %i2, %i3
; CHECK: restore %g0, %i3, %o0
define i32 @selecti32_xcc(i64 %x, i64 %y, i32 %a, i32 %b) {
entry:
%tobool = icmp sgt i64 %x, %y
%rv = select i1 %tobool, i32 %a, i32 %b
ret i32 %rv
}
; CHECK: selecti64_xcc
; CHECK: cmp %i0, %i1
; CHECK: movg %xcc, %i2, %i3
; CHECK: restore %g0, %i3, %o0
define i64 @selecti64_xcc(i64 %x, i64 %y, i64 %a, i64 %b) {
entry:
%tobool = icmp sgt i64 %x, %y
%rv = select i1 %tobool, i64 %a, i64 %b
ret i64 %rv
}
; CHECK: selecti64_icc
; CHECK: cmp %i0, %i1
; CHECK: movg %icc, %i2, %i3
; CHECK: restore %g0, %i3, %o0
define i64 @selecti64_icc(i32 %x, i32 %y, i64 %a, i64 %b) {
entry:
%tobool = icmp sgt i32 %x, %y
%rv = select i1 %tobool, i64 %a, i64 %b
ret i64 %rv
}
; CHECK: selecti64_fcc
; CHECK: fcmps %f1, %f3
; CHECK: movul %fcc0, %i2, %i3
; CHECK: restore %g0, %i3, %o0
define i64 @selecti64_fcc(float %x, float %y, i64 %a, i64 %b) {
entry:
%tobool = fcmp ult float %x, %y
%rv = select i1 %tobool, i64 %a, i64 %b
ret i64 %rv
}
; CHECK: selectf32_xcc
; CHECK: cmp %i0, %i1
; CHECK: fmovsg %xcc, %f5, %f7
; CHECK: fmovs %f7, %f1
define float @selectf32_xcc(i64 %x, i64 %y, float %a, float %b) {
entry:
%tobool = icmp sgt i64 %x, %y
%rv = select i1 %tobool, float %a, float %b
ret float %rv
}
; CHECK: selectf64_xcc
; CHECK: cmp %i0, %i1
; CHECK: fmovdg %xcc, %f4, %f6
; CHECK: fmovd %f6, %f0
define double @selectf64_xcc(i64 %x, i64 %y, double %a, double %b) {
entry:
%tobool = icmp sgt i64 %x, %y
%rv = select i1 %tobool, double %a, double %b
ret double %rv
}
; The MOVXCC instruction can't use %g0 for its tied operand.
; CHECK: select_consti64_xcc
; CHECK: cmp
; CHECK: movg %xcc, 123, %i{{[0-2]}}
define i64 @select_consti64_xcc(i64 %x, i64 %y) {
entry:
%tobool = icmp sgt i64 %x, %y
%rv = select i1 %tobool, i64 123, i64 0
ret i64 %rv
}