reference, declarationdefinition
definition → references, declarations, derived classes, virtual overrides
reference to multiple definitions → definitions
unreferenced
    1
    2
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
  100
  101
  102
  103
  104
  105
  106
  107
  108
  109
  110
  111
  112
  113
  114
  115
  116
  117
  118
  119
  120
  121
  122
  123
  124
  125
  126
  127
  128
  129
  130
  131
  132
  133
  134
  135
  136
  137
  138
  139
  140
  141
  142
  143
  144
  145
  146
  147
  148
  149
  150
  151
  152
  153
  154
  155
  156
  157
  158
  159
  160
  161
  162
  163
  164
  165
  166
  167
  168
  169
  170
  171
  172
  173
  174
  175
  176
  177
  178
  179
  180
  181
  182
  183
  184
  185
  186
  187
  188
  189
  190
  191
  192
  193
  194
  195
  196
  197
  198
  199
  200
  201
  202
  203
  204
  205
  206
  207
  208
  209
  210
  211
  212
  213
  214
  215
  216
  217
  218
  219
  220
  221
  222
  223
  224
  225
; RUN: llc -mtriple=armv4t-eabi %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=V4T
; RUN: llc -mtriple=armv6t2-eabi %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=V6T2

; Check for several conditions that should result in SSAT.
; For example, the base test is equivalent to
; x < -k ? -k : (x > k ? k : x) in C. All patterns that bound x
; to the interval [-k, k] where k is a power of 2 can be
; transformed into SSAT. At the end there are some tests
; checking that conditionals are not transformed if they don't
; match the right pattern.

;
; Base tests with different bit widths
;

; x < -k ? -k : (x > k ? k : x)
; 32-bit base test
define i32 @sat_base_32bit(i32 %x) #0 {
; CHECK-LABEL: sat_base_32bit:
; V6T2: ssat r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpLow = icmp slt i32 %x, -8388608
  %cmpUp = icmp sgt i32 %x, 8388607
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %x
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %saturateUp
  ret i32 %saturateLow
}

; x < -k ? -k : (x > k ? k : x)
; 16-bit base test
define i16 @sat_base_16bit(i16 %x) #0 {
; CHECK-LABEL: sat_base_16bit:
; V6T2: ssat r0, #12, r0
; V4T-NOT: ssat
entry:
  %cmpLow = icmp slt i16 %x, -2048
  %cmpUp = icmp sgt i16 %x, 2047
  %saturateUp = select i1 %cmpUp, i16 2047, i16 %x
  %saturateLow = select i1 %cmpLow, i16 -2048, i16 %saturateUp
  ret i16 %saturateLow
}

; x < -k ? -k : (x > k ? k : x)
; 8-bit base test
define i8 @sat_base_8bit(i8 %x) #0 {
; CHECK-LABEL: sat_base_8bit:
; V6T2: ssat r0, #6, r0
; V4T-NOT: ssat
entry:
  %cmpLow = icmp slt i8 %x, -32
  %cmpUp = icmp sgt i8 %x, 31
  %saturateUp = select i1 %cmpUp, i8 31, i8 %x
  %saturateLow = select i1 %cmpLow, i8 -32, i8 %saturateUp
  ret i8 %saturateLow
}

;
; Tests where the conditionals that check for upper and lower bounds,
; or the < and > operators, are arranged in different ways. Only some
; of the possible combinations that lead to SSAT are tested.
;

; x < -k ? -k : (x < k ? x : k)
define i32 @sat_lower_upper_1(i32 %x) #0 {
; CHECK-LABEL: sat_lower_upper_1:
; V6T2: ssat r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpLow = icmp slt i32 %x, -8388608
  %cmpUp = icmp slt i32 %x, 8388607
  %saturateUp = select i1 %cmpUp, i32 %x, i32 8388607
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %saturateUp
  ret i32 %saturateLow
}

; x > -k ? (x > k ? k : x) : -k
define i32 @sat_lower_upper_2(i32 %x) #0 {
; CHECK-LABEL: sat_lower_upper_2:
; V6T2: ssat    r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpLow = icmp sgt i32 %x, -8388608
  %cmpUp = icmp sgt i32 %x, 8388607
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %x
  %saturateLow = select i1 %cmpLow, i32 %saturateUp, i32 -8388608
  ret i32 %saturateLow
}

; x < k ? (x < -k ? -k : x) : k
define i32 @sat_upper_lower_1(i32 %x) #0 {
; CHECK-LABEL: sat_upper_lower_1:
; V6T2: ssat    r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpUp = icmp slt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %x
  %saturateUp = select i1 %cmpUp, i32 %saturateLow, i32 8388607
  ret i32 %saturateUp
}

; x > k ? k : (x < -k ? -k : x)
define i32 @sat_upper_lower_2(i32 %x) #0 {
; CHECK-LABEL: sat_upper_lower_2:
; V6T2: ssat    r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; k < x ? k : (x > -k ? x : -k)
define i32 @sat_upper_lower_3(i32 %x) #0 {
; CHECK-LABEL: sat_upper_lower_3:
; V6T2: ssat    r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpUp = icmp slt i32 8388607, %x
  %cmpLow = icmp sgt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 %x, i32 -8388608
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

;
; Miscellanea
;

; Check that >= and <= work the same as > and <
; k <= x ? k : (x >= -k ? x : -k)
define i32 @sat_le_ge(i32 %x) #0 {
; CHECK-LABEL: sat_le_ge:
; V6T2: ssat    r0, #24, r0
; V4T-NOT: ssat
entry:
  %cmpUp = icmp sle i32 8388607, %x
  %cmpLow = icmp sge i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 %x, i32 -8388608
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

;
; The following tests check for patterns that should not transform
; into SSAT but are similar enough that could confuse the selector.
;

; x > k ? k : (x > -k ? -k : x)
; First condition upper-saturates, second doesn't lower-saturate.
define i32 @no_sat_missing_lower(i32 %x) #0 {
; CHECK-LABEL: no_sat_missing_lower
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp sgt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; x < k ? k : (x < -k ? -k : x)
; Second condition lower-saturates, first doesn't upper-saturate.
define i32 @no_sat_missing_upper(i32 %x) #0 {
; CHECK-LABEL: no_sat_missing_upper:
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp slt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; Lower constant is different in the select and in the compare
define i32 @no_sat_incorrect_constant(i32 %x) #0 {
; CHECK-LABEL: no_sat_incorrect_constant:
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388607, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; The interval is not [k, ~k]
define i32 @no_sat_incorrect_interval(i32 %x) #0 {
; CHECK-LABEL: no_sat_incorrect_interval:
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -19088744
  %saturateLow = select i1 %cmpLow, i32 -19088744, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; The returned value (y) is not the same as the tested value (x).
define i32 @no_sat_incorrect_return(i32 %x, i32 %y) #0 {
; CHECK-LABEL: no_sat_incorrect_return:
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp slt i32 %x, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %y
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}

; One of the values in a compare (y) is not the same as the rest
; of the compare and select values (x).
define i32 @no_sat_incorrect_compare(i32 %x, i32 %y) #0 {
; CHECK-LABEL: no_sat_incorrect_compare:
; CHECK-NOT: ssat
entry:
  %cmpUp = icmp sgt i32 %x, 8388607
  %cmpLow = icmp slt i32 %y, -8388608
  %saturateLow = select i1 %cmpLow, i32 -8388608, i32 %x
  %saturateUp = select i1 %cmpUp, i32 8388607, i32 %saturateLow
  ret i32 %saturateUp
}