1 ; RUN: opt < %s -ipsccp -S | FileCheck %s 2 ; PR36485 3 ; musttail call result can\'t be replaced with a constant, unless the call 4 ; can be removed 5 6 declare i32 @external() 7 8 define i8* @start(i8 %v) { 9 %c1 = icmp eq i8 %v, 0 10 br i1 %c1, label %true, label %false 11 true: 12 ; CHECK: %ca = musttail call i8* @side_effects(i8 %v) 13 ; CHECK: ret i8* %ca 14 %ca = musttail call i8* @side_effects(i8 %v) 15 ret i8* %ca 16 false: 17 %c2 = icmp eq i8 %v, 1 18 br i1 %c2, label %c2_true, label %c2_false 19 c2_true: 20 %ca1 = musttail call i8* @no_side_effects(i8 %v) 21 ; CHECK: ret i8* null 22 ret i8* %ca1 23 c2_false: 24 ; CHECK: %ca2 = musttail call i8* @dont_zap_me(i8 %v) 25 ; CHECK: ret i8* %ca2 26 %ca2 = musttail call i8* @dont_zap_me(i8 %v) 27 ret i8* %ca2 28 } 29 30 define internal i8* @side_effects(i8 %v) { 31 %i1 = call i32 @external() 32 33 ; since this goes back to `start` the SCPP should be see that the return value 34 ; is always `null`. 35 ; The call can't be removed due to `external` call above, though. 36 37 ; CHECK: %ca = musttail call i8* @start(i8 %v) 38 %ca = musttail call i8* @start(i8 %v) 39 40 ; Thus the result must be returned anyway 41 ; CHECK: ret i8* %ca 42 ret i8* %ca 43 } 44 45 define internal i8* @no_side_effects(i8 %v) readonly nounwind { 46 ; The call to this function is removed, so the return value must be zapped 47 ; CHECK: ret i8* undef 48 ret i8* null 49 } 50 51 define internal i8* @dont_zap_me(i8 %v) { 52 %i1 = call i32 @external() 53 54 ; The call to this function cannot be removed due to side effects. Thus the 55 ; return value should stay as it is, and should not be zapped. 56 ; CHECK: ret i8* null 57 ret i8* null 58 } 59
