1 ; RUN: opt < %s -basicaa -gvn -instcombine -S | FileCheck %s 2 3 declare i32* @test(i32* nocapture) 4 5 define i32 @test2() { 6 ; CHECK: ret i32 0 7 %P = alloca i32 8 %Q = call i32* @test(i32* %P) 9 %a = load i32* %P 10 store i32 4, i32* %Q ;; cannot clobber P since it is nocapture. 11 %b = load i32* %P 12 %c = sub i32 %a, %b 13 ret i32 %c 14 } 15 16 declare void @test3(i32** %p, i32* %q) nounwind 17 18 define i32 @test4(i32* noalias nocapture %p) nounwind { 19 ; CHECK: call void @test3 20 ; CHECK: store i32 0, i32* %p 21 ; CHECK: store i32 1, i32* %x 22 ; CHECK: %y = load i32* %p 23 ; CHECK: ret i32 %y 24 entry: 25 %q = alloca i32* 26 ; Here test3 might store %p to %q. This doesn't violate %p's nocapture 27 ; attribute since the copy doesn't outlive the function. 28 call void @test3(i32** %q, i32* %p) nounwind 29 store i32 0, i32* %p 30 %x = load i32** %q 31 ; This store might write to %p and so we can't eliminate the subsequent 32 ; load 33 store i32 1, i32* %x 34 %y = load i32* %p 35 ret i32 %y 36 } 37
