llvm-6502/test/CodeGen/SystemZ/atomicrmw-xor-02.ll
Richard Sandiford 6824f127f9 [SystemZ] Be more careful about inverting CC masks
System z branches have a mask to select which of the 4 CC values should
cause the branch to be taken.  We can invert a branch by inverting the mask.
However, not all instructions can produce all 4 CC values, so inverting
the branch like this can lead to some oddities.  For example, integer
comparisons only produce a CC of 0 (equal), 1 (less) or 2 (greater).
If an integer EQ is reversed to NE before instruction selection,
the branch will test for 1 or 2.  If instead the branch is reversed
after instruction selection (by inverting the mask), it will test for
1, 2 or 3.  Both are correct, but the second isn't really canonical.
This patch therefore keeps track of which CC values are possible
and uses this when inverting a mask.

Although this is mostly cosmestic, it fixes undefined behavior
for the CIJNLH in branch-08.ll.  Another fix would have been
to mask out bit 0 when generating the fused compare and branch,
but the point of this patch is that we shouldn't need to do that
in the first place.

The patch also makes it easier to reuse CC results from other instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187495 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-31 12:30:20 +00:00

133 lines
3.8 KiB
LLVM

; Test 16-bit atomic XORs.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s -check-prefix=CHECK
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s -check-prefix=CHECK-SHIFT1
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s -check-prefix=CHECK-SHIFT2
; Check XOR of a variable.
; - CHECK is for the main loop.
; - CHECK-SHIFT1 makes sure that the negated shift count used by the second
; RLL is set up correctly. The negation is independent of the NILL and L
; tested in CHECK.
; - CHECK-SHIFT2 makes sure that %b is shifted into the high part of the word
; before being used. This shift is independent of the other loop prologue
; instructions.
define i16 @f1(i16 *%src, i16 %b) {
; CHECK-LABEL: f1:
; CHECK: sllg [[SHIFT:%r[1-9]+]], %r2, 3
; CHECK: nill %r2, 65532
; CHECK: l [[OLD:%r[0-9]+]], 0(%r2)
; CHECK: [[LABEL:\.[^:]*]]:
; CHECK: rll [[ROT:%r[0-9]+]], [[OLD]], 0([[SHIFT]])
; CHECK: xr [[ROT]], %r3
; CHECK: rll [[NEW:%r[0-9]+]], [[ROT]], 0({{%r[1-9]+}})
; CHECK: cs [[OLD]], [[NEW]], 0(%r2)
; CHECK: jl [[LABEL]]
; CHECK: rll %r2, [[OLD]], 16([[SHIFT]])
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f1:
; CHECK-SHIFT1: sllg [[SHIFT:%r[1-9]+]], %r2, 3
; CHECK-SHIFT1: lcr [[NEGSHIFT:%r[1-9]+]], [[SHIFT]]
; CHECK-SHIFT1: rll
; CHECK-SHIFT1: rll {{%r[0-9]+}}, {{%r[0-9]+}}, 0([[NEGSHIFT]])
; CHECK-SHIFT1: rll
; CHECK-SHIFT1: br %r14
;
; CHECK-SHIFT2-LABEL: f1:
; CHECK-SHIFT2: sll %r3, 16
; CHECK-SHIFT2: rll
; CHECK-SHIFT2: xr {{%r[0-9]+}}, %r3
; CHECK-SHIFT2: rll
; CHECK-SHIFT2: rll
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 %b seq_cst
ret i16 %res
}
; Check the minimum signed value. We XOR the rotated word with 0x80000000.
define i16 @f2(i16 *%src) {
; CHECK-LABEL: f2:
; CHECK: sllg [[SHIFT:%r[1-9]+]], %r2, 3
; CHECK: nill %r2, 65532
; CHECK: l [[OLD:%r[0-9]+]], 0(%r2)
; CHECK: [[LABEL:\.[^:]*]]:
; CHECK: rll [[ROT:%r[0-9]+]], [[OLD]], 0([[SHIFT]])
; CHECK: xilf [[ROT]], 2147483648
; CHECK: rll [[NEW:%r[0-9]+]], [[ROT]], 0([[NEGSHIFT:%r[1-9]+]])
; CHECK: cs [[OLD]], [[NEW]], 0(%r2)
; CHECK: jl [[LABEL]]
; CHECK: rll %r2, [[OLD]], 16([[SHIFT]])
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f2:
; CHECK-SHIFT1: sllg [[SHIFT:%r[1-9]+]], %r2, 3
; CHECK-SHIFT1: lcr [[NEGSHIFT:%r[1-9]+]], [[SHIFT]]
; CHECK-SHIFT1: rll
; CHECK-SHIFT1: rll {{%r[0-9]+}}, {{%r[0-9]+}}, 0([[NEGSHIFT]])
; CHECK-SHIFT1: rll
; CHECK-SHIFT1: br %r14
;
; CHECK-SHIFT2-LABEL: f2:
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 -32768 seq_cst
ret i16 %res
}
; Check XORs of -1. We XOR the rotated word with 0xffff0000.
define i16 @f3(i16 *%src) {
; CHECK-LABEL: f3:
; CHECK: xilf [[ROT]], 4294901760
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f3:
; CHECK-SHIFT1: br %r14
; CHECK-SHIFT2-LABEL: f3:
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 -1 seq_cst
ret i16 %res
}
; Check XORs of 1. We XOR the rotated word with 0x00010000.
define i16 @f4(i16 *%src) {
; CHECK-LABEL: f4:
; CHECK: xilf [[ROT]], 65536
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f4:
; CHECK-SHIFT1: br %r14
; CHECK-SHIFT2-LABEL: f4:
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 1 seq_cst
ret i16 %res
}
; Check the maximum signed value. We XOR the rotated word with 0x7fff0000.
define i16 @f5(i16 *%src) {
; CHECK-LABEL: f5:
; CHECK: xilf [[ROT]], 2147418112
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f5:
; CHECK-SHIFT1: br %r14
; CHECK-SHIFT2-LABEL: f5:
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 32767 seq_cst
ret i16 %res
}
; Check XORs of a large unsigned value. We XOR the rotated word with
; 0xfffd0000.
define i16 @f6(i16 *%src) {
; CHECK-LABEL: f6:
; CHECK: xilf [[ROT]], 4294770688
; CHECK: br %r14
;
; CHECK-SHIFT1-LABEL: f6:
; CHECK-SHIFT1: br %r14
; CHECK-SHIFT2-LABEL: f6:
; CHECK-SHIFT2: br %r14
%res = atomicrmw xor i16 *%src, i16 65533 seq_cst
ret i16 %res
}