1 ; bswap should be constant folded when it is passed a constant argument 2 3 ; RUN: llc < %s -march=x86 -mcpu=i686 | FileCheck %s 4 ; RUN: llc < %s -march=x86-64 | FileCheck %s --check-prefix=CHECK64 5 6 declare i16 @llvm.bswap.i16(i16) 7 8 declare i32 @llvm.bswap.i32(i32) 9 10 declare i64 @llvm.bswap.i64(i64) 11 12 define i16 @W(i16 %A) { 13 ; CHECK-LABEL: W: 14 ; CHECK: rolw $8, %ax 15 16 ; CHECK64-LABEL: W: 17 ; CHECK64: rolw $8, % 18 %Z = call i16 @llvm.bswap.i16( i16 %A ) ; <i16> [#uses=1] 19 ret i16 %Z 20 } 21 22 define i32 @X(i32 %A) { 23 ; CHECK-LABEL: X: 24 ; CHECK: bswapl %eax 25 26 ; CHECK64-LABEL: X: 27 ; CHECK64: bswapl % 28 %Z = call i32 @llvm.bswap.i32( i32 %A ) ; <i32> [#uses=1] 29 ret i32 %Z 30 } 31 32 define i64 @Y(i64 %A) { 33 ; CHECK-LABEL: Y: 34 ; CHECK: bswapl %eax 35 ; CHECK: bswapl %edx 36 37 ; CHECK64-LABEL: Y: 38 ; CHECK64: bswapq % 39 %Z = call i64 @llvm.bswap.i64( i64 %A ) ; <i64> [#uses=1] 40 ret i64 %Z 41 } 42 43 ; rdar://9164521 44 define i32 @test1(i32 %a) nounwind readnone { 45 entry: 46 ; CHECK-LABEL: test1: 47 ; CHECK: bswapl [[REG:%.*]] 48 ; CHECK: shrl $16, [[REG]] 49 50 ; CHECK64-LABEL: test1: 51 ; CHECK64: bswapl [[REG:%.*]] 52 ; CHECK64: shrl $16, [[REG]] 53 %and = lshr i32 %a, 8 54 %shr3 = and i32 %and, 255 55 %and2 = shl i32 %a, 8 56 %shl = and i32 %and2, 65280 57 %or = or i32 %shr3, %shl 58 ret i32 %or 59 } 60 61 define i32 @test2(i32 %a) nounwind readnone { 62 entry: 63 ; CHECK-LABEL: test2: 64 ; CHECK: bswapl [[REG:%.*]] 65 ; CHECK: sarl $16, [[REG]] 66 67 ; CHECK64-LABEL: test2: 68 ; CHECK64: bswapl [[REG:%.*]] 69 ; CHECK64: sarl $16, [[REG]] 70 %and = lshr i32 %a, 8 71 %shr4 = and i32 %and, 255 72 %and2 = shl i32 %a, 8 73 %or = or i32 %shr4, %and2 74 %sext = shl i32 %or, 16 75 %conv3 = ashr exact i32 %sext, 16 76 ret i32 %conv3 77 } 78 79 @var8 = global i8 0 80 @var16 = global i16 0 81 82 ; The "shl" below can move bits into the high parts of the value, so the 83 ; operation is not a "bswap, shr" pair. 84 85 ; rdar://problem/14814049 86 define i64 @not_bswap() { 87 ; CHECK-LABEL: not_bswap: 88 ; CHECK-NOT: bswapl 89 ; CHECK: ret 90 91 ; CHECK64-LABEL: not_bswap: 92 ; CHECK64-NOT: bswapq 93 ; CHECK64: ret 94 %init = load i16, i16* @var16 95 %big = zext i16 %init to i64 96 97 %hishifted = lshr i64 %big, 8 98 %loshifted = shl i64 %big, 8 99 100 %notswapped = or i64 %hishifted, %loshifted 101 102 ret i64 %notswapped 103 } 104 105 ; This time, the lshr (and subsequent or) is completely useless. While it's 106 ; technically correct to convert this into a "bswap, shr", it's suboptimal. A 107 ; simple shl works better. 108 109 define i64 @not_useful_bswap() { 110 ; CHECK-LABEL: not_useful_bswap: 111 ; CHECK-NOT: bswapl 112 ; CHECK: ret 113 114 ; CHECK64-LABEL: not_useful_bswap: 115 ; CHECK64-NOT: bswapq 116 ; CHECK64: ret 117 118 %init = load i8, i8* @var8 119 %big = zext i8 %init to i64 120 121 %hishifted = lshr i64 %big, 8 122 %loshifted = shl i64 %big, 8 123 124 %notswapped = or i64 %hishifted, %loshifted 125 126 ret i64 %notswapped 127 } 128 129 ; Finally, it *is* OK to just mask off the shl if we know that the value is zero 130 ; beyond 16 bits anyway. This is a legitimate bswap. 131 132 define i64 @finally_useful_bswap() { 133 ; CHECK-LABEL: finally_useful_bswap: 134 ; CHECK: bswapl [[REG:%.*]] 135 ; CHECK: shrl $16, [[REG]] 136 ; CHECK: ret 137 138 ; CHECK64-LABEL: finally_useful_bswap: 139 ; CHECK64: bswapq [[REG:%.*]] 140 ; CHECK64: shrq $48, [[REG]] 141 ; CHECK64: ret 142 143 %init = load i16, i16* @var16 144 %big = zext i16 %init to i64 145 146 %hishifted = lshr i64 %big, 8 147 %lomasked = and i64 %big, 255 148 %loshifted = shl i64 %lomasked, 8 149 150 %swapped = or i64 %hishifted, %loshifted 151 152 ret i64 %swapped 153 } 154 155
