musttail-call.ll
2.55 KB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes
; RUN: opt -S -passes=attributor -aa-pipeline='basic-aa' -attributor-disable=false -attributor-max-iterations-verify -attributor-max-iterations=4 < %s | FileCheck %s
; PR36485
; musttail call result can't be replaced with a constant, unless the call can be removed
declare i32 @external()
define i8* @start(i8 %v) {
; CHECK-LABEL: define {{[^@]+}}@start
; CHECK-SAME: (i8 [[V:%.*]])
; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[V]], 0
; CHECK-NEXT: br i1 [[C1]], label [[TRUE:%.*]], label [[FALSE:%.*]]
; CHECK: true:
; CHECK-NEXT: [[CA:%.*]] = musttail call i8* @side_effects(i8 [[V]])
; CHECK-NEXT: ret i8* [[CA]]
; CHECK: false:
; CHECK-NEXT: [[C2:%.*]] = icmp eq i8 [[V]], 1
; CHECK-NEXT: br i1 [[C2]], label [[C2_TRUE:%.*]], label [[C2_FALSE:%.*]]
; CHECK: c2_true:
; CHECK-NEXT: [[CA1:%.*]] = musttail call i8* @no_side_effects(i8 undef)
; CHECK-NEXT: ret i8* [[CA1]]
; CHECK: c2_false:
; CHECK-NEXT: [[CA2:%.*]] = musttail call i8* @dont_zap_me(i8 undef)
; CHECK-NEXT: ret i8* [[CA2]]
;
%c1 = icmp eq i8 %v, 0
br i1 %c1, label %true, label %false
true:
; FIXME: propagate the value information for %v
%ca = musttail call i8* @side_effects(i8 %v)
ret i8* %ca
false:
%c2 = icmp eq i8 %v, 1
br i1 %c2, label %c2_true, label %c2_false
c2_true:
%ca1 = musttail call i8* @no_side_effects(i8 %v)
; FIXME: zap this call
ret i8* %ca1
c2_false:
%ca2 = musttail call i8* @dont_zap_me(i8 %v)
ret i8* %ca2
}
define internal i8* @side_effects(i8 %v) {
; CHECK-LABEL: define {{[^@]+}}@side_effects
; CHECK-SAME: (i8 [[V:%.*]])
; CHECK-NEXT: [[I1:%.*]] = call i32 @external()
; CHECK-NEXT: [[CA:%.*]] = musttail call i8* @start(i8 [[V]])
; CHECK-NEXT: ret i8* [[CA]]
;
%i1 = call i32 @external()
; since this goes back to `start` the SCPP should be see that the return value
; is always `null`.
; The call can't be removed due to `external` call above, though.
%ca = musttail call i8* @start(i8 %v)
; Thus the result must be returned anyway
ret i8* %ca
}
define internal i8* @no_side_effects(i8 %v) readonly nounwind {
; CHECK-LABEL: define {{[^@]+}}@no_side_effects
; CHECK-SAME: (i8 [[V:%.*]])
; CHECK-NEXT: ret i8* null
;
ret i8* null
}
define internal i8* @dont_zap_me(i8 %v) {
; CHECK-LABEL: define {{[^@]+}}@dont_zap_me
; CHECK-SAME: (i8 [[V:%.*]])
; CHECK-NEXT: [[I1:%.*]] = call i32 @external()
; CHECK-NEXT: ret i8* null
;
%i1 = call i32 @external()
ret i8* null
}