1 ; RUN: opt < %s -basicaa -licm -S | FileCheck %s 2 3 declare i32 @strlen(i8*) readonly 4 5 declare void @foo() 6 7 ; Sink readonly function. 8 define i32 @test1(i8* %P) { 9 br label %Loop 10 11 Loop: ; preds = %Loop, %0 12 %A = call i32 @strlen( i8* %P ) readonly 13 br i1 false, label %Loop, label %Out 14 15 Out: ; preds = %Loop 16 ret i32 %A 17 ; CHECK: @test1 18 ; CHECK: Out: 19 ; CHECK-NEXT: call i32 @strlen 20 ; CHECK-NEXT: ret i32 %A 21 } 22 23 declare double @sin(double) readnone 24 25 ; Sink readnone function out of loop with unknown memory behavior. 26 define double @test2(double %X) { 27 br label %Loop 28 29 Loop: ; preds = %Loop, %0 30 call void @foo( ) 31 %A = call double @sin( double %X ) readnone 32 br i1 true, label %Loop, label %Out 33 34 Out: ; preds = %Loop 35 ret double %A 36 ; CHECK: @test2 37 ; CHECK: Out: 38 ; CHECK-NEXT: call double @sin 39 ; CHECK-NEXT: ret double %A 40 } 41 42 ; This testcase checks to make sure the sinker does not cause problems with 43 ; critical edges. 44 define void @test3() { 45 Entry: 46 br i1 false, label %Loop, label %Exit 47 Loop: 48 %X = add i32 0, 1 49 br i1 false, label %Loop, label %Exit 50 Exit: 51 %Y = phi i32 [ 0, %Entry ], [ %X, %Loop ] 52 ret void 53 54 ; CHECK: @test3 55 ; CHECK: Exit.loopexit: 56 ; CHECK-NEXT: %X = add i32 0, 1 57 ; CHECK-NEXT: br label %Exit 58 59 } 60 61 ; If the result of an instruction is only used outside of the loop, sink 62 ; the instruction to the exit blocks instead of executing it on every 63 ; iteration of the loop. 64 ; 65 define i32 @test4(i32 %N) { 66 Entry: 67 br label %Loop 68 Loop: ; preds = %Loop, %Entry 69 %N_addr.0.pn = phi i32 [ %dec, %Loop ], [ %N, %Entry ] 70 %tmp.6 = mul i32 %N, %N_addr.0.pn ; <i32> [#uses=1] 71 %tmp.7 = sub i32 %tmp.6, %N ; <i32> [#uses=1] 72 %dec = add i32 %N_addr.0.pn, -1 ; <i32> [#uses=1] 73 %tmp.1 = icmp ne i32 %N_addr.0.pn, 1 ; <i1> [#uses=1] 74 br i1 %tmp.1, label %Loop, label %Out 75 Out: ; preds = %Loop 76 ret i32 %tmp.7 77 ; CHECK: @test4 78 ; CHECK: Out: 79 ; CHECK-NEXT: mul i32 %N, %N_addr.0.pn 80 ; CHECK-NEXT: sub i32 %tmp.6, %N 81 ; CHECK-NEXT: ret i32 82 } 83 84 ; To reduce register pressure, if a load is hoistable out of the loop, and the 85 ; result of the load is only used outside of the loop, sink the load instead of 86 ; hoisting it! 87 ; 88 @X = global i32 5 ; <i32*> [#uses=1] 89 90 define i32 @test5(i32 %N) { 91 Entry: 92 br label %Loop 93 Loop: ; preds = %Loop, %Entry 94 %N_addr.0.pn = phi i32 [ %dec, %Loop ], [ %N, %Entry ] 95 %tmp.6 = load i32* @X ; <i32> [#uses=1] 96 %dec = add i32 %N_addr.0.pn, -1 ; <i32> [#uses=1] 97 %tmp.1 = icmp ne i32 %N_addr.0.pn, 1 ; <i1> [#uses=1] 98 br i1 %tmp.1, label %Loop, label %Out 99 Out: ; preds = %Loop 100 ret i32 %tmp.6 101 ; CHECK: @test5 102 ; CHECK: Out: 103 ; CHECK-NEXT: %tmp.6 = load i32* @X 104 ; CHECK-NEXT: ret i32 %tmp.6 105 } 106 107 108 109 ; The loop sinker was running from the bottom of the loop to the top, causing 110 ; it to miss opportunities to sink instructions that depended on sinking other 111 ; instructions from the loop. Instead they got hoisted, which is better than 112 ; leaving them in the loop, but increases register pressure pointlessly. 113 114 %Ty = type { i32, i32 } 115 @X2 = external global %Ty 116 117 define i32 @test6() { 118 br label %Loop 119 Loop: 120 %dead = getelementptr %Ty* @X2, i64 0, i32 0 121 %sunk2 = load i32* %dead 122 br i1 false, label %Loop, label %Out 123 Out: ; preds = %Loop 124 ret i32 %sunk2 125 ; CHECK: @test6 126 ; CHECK: Out: 127 ; CHECK-NEXT: %dead = getelementptr %Ty* @X2, i64 0, i32 0 128 ; CHECK-NEXT: %sunk2 = load i32* %dead 129 ; CHECK-NEXT: ret i32 %sunk2 130 } 131 132 133 134 ; This testcase ensures that we can sink instructions from loops with 135 ; multiple exits. 136 ; 137 define i32 @test7(i32 %N, i1 %C) { 138 Entry: 139 br label %Loop 140 Loop: ; preds = %ContLoop, %Entry 141 %N_addr.0.pn = phi i32 [ %dec, %ContLoop ], [ %N, %Entry ] 142 %tmp.6 = mul i32 %N, %N_addr.0.pn 143 %tmp.7 = sub i32 %tmp.6, %N ; <i32> [#uses=2] 144 %dec = add i32 %N_addr.0.pn, -1 ; <i32> [#uses=1] 145 br i1 %C, label %ContLoop, label %Out1 146 ContLoop: 147 %tmp.1 = icmp ne i32 %N_addr.0.pn, 1 148 br i1 %tmp.1, label %Loop, label %Out2 149 Out1: ; preds = %Loop 150 ret i32 %tmp.7 151 Out2: ; preds = %ContLoop 152 ret i32 %tmp.7 153 ; CHECK: @test7 154 ; CHECK: Out1: 155 ; CHECK-NEXT: mul i32 %N, %N_addr.0.pn 156 ; CHECK-NEXT: sub i32 %tmp.6, %N 157 ; CHECK-NEXT: ret 158 ; CHECK: Out2: 159 ; CHECK-NEXT: mul i32 %N, %N_addr.0.pn 160 ; CHECK-NEXT: sub i32 %tmp.6 161 ; CHECK-NEXT: ret 162 } 163 164 165 ; This testcase checks to make sure we can sink values which are only live on 166 ; some exits out of the loop, and that we can do so without breaking dominator 167 ; info. 168 define i32 @test8(i1 %C1, i1 %C2, i32* %P, i32* %Q) { 169 Entry: 170 br label %Loop 171 Loop: ; preds = %Cont, %Entry 172 br i1 %C1, label %Cont, label %exit1 173 Cont: ; preds = %Loop 174 %X = load i32* %P ; <i32> [#uses=2] 175 store i32 %X, i32* %Q 176 %V = add i32 %X, 1 ; <i32> [#uses=1] 177 br i1 %C2, label %Loop, label %exit2 178 exit1: ; preds = %Loop 179 ret i32 0 180 exit2: ; preds = %Cont 181 ret i32 %V 182 ; CHECK: @test8 183 ; CHECK: exit1: 184 ; CHECK-NEXT: ret i32 0 185 ; CHECK: exit2: 186 ; CHECK-NEXT: %V = add i32 %X, 1 187 ; CHECK-NEXT: ret i32 %V 188 } 189 190 191 define void @test9() { 192 loopentry.2.i: 193 br i1 false, label %no_exit.1.i.preheader, label %loopentry.3.i.preheader 194 no_exit.1.i.preheader: ; preds = %loopentry.2.i 195 br label %no_exit.1.i 196 no_exit.1.i: ; preds = %endif.8.i, %no_exit.1.i.preheader 197 br i1 false, label %return.i, label %endif.8.i 198 endif.8.i: ; preds = %no_exit.1.i 199 %inc.1.i = add i32 0, 1 ; <i32> [#uses=1] 200 br i1 false, label %no_exit.1.i, label %loopentry.3.i.preheader.loopexit 201 loopentry.3.i.preheader.loopexit: ; preds = %endif.8.i 202 br label %loopentry.3.i.preheader 203 loopentry.3.i.preheader: ; preds = %loopentry.3.i.preheader.loopexit, %loopentry.2.i 204 %arg_num.0.i.ph13000 = phi i32 [ 0, %loopentry.2.i ], [ %inc.1.i, %loopentry.3.i.preheader.loopexit ] ; <i32> [#uses=0] 205 ret void 206 return.i: ; preds = %no_exit.1.i 207 ret void 208 209 ; CHECK: @test9 210 ; CHECK: loopentry.3.i.preheader.loopexit: 211 ; CHECK-NEXT: %inc.1.i = add i32 0, 1 212 ; CHECK-NEXT: br label %loopentry.3.i.preheader 213 } 214 215 216 ; Potentially trapping instructions may be sunk as long as they are guaranteed 217 ; to be executed. 218 define i32 @test10(i32 %N) { 219 Entry: 220 br label %Loop 221 Loop: ; preds = %Loop, %Entry 222 %N_addr.0.pn = phi i32 [ %dec, %Loop ], [ %N, %Entry ] ; <i32> [#uses=3] 223 %tmp.6 = sdiv i32 %N, %N_addr.0.pn ; <i32> [#uses=1] 224 %dec = add i32 %N_addr.0.pn, -1 ; <i32> [#uses=1] 225 %tmp.1 = icmp ne i32 %N_addr.0.pn, 0 ; <i1> [#uses=1] 226 br i1 %tmp.1, label %Loop, label %Out 227 Out: ; preds = %Loop 228 ret i32 %tmp.6 229 230 ; CHECK: @test10 231 ; CHECK: Out: 232 ; CHECK-NEXT: %tmp.6 = sdiv i32 %N, %N_addr.0.pn 233 ; CHECK-NEXT: ret i32 %tmp.6 234 } 235 236 ; Should delete, not sink, dead instructions. 237 define void @test11() { 238 br label %Loop 239 Loop: 240 %dead = getelementptr %Ty* @X2, i64 0, i32 0 241 br i1 false, label %Loop, label %Out 242 Out: 243 ret void 244 ; CHECK: @test11 245 ; CHECK: Out: 246 ; CHECK-NEXT: ret void 247 } 248 249 250
