1 ; RUN: opt < %s -globals-aa -gvn -S | FileCheck %s 2 ; 3 ; This tests the safe no-alias conclusions of GMR -- when there is 4 ; a non-escaping global as one indentified underlying object and some pointer 5 ; that would inherently have escaped any other function as the other underlying 6 ; pointer of an alias query. 7 8 @g1 = internal global i32 0 9 10 define i32 @test1(i32* %param) { 11 ; Ensure that we can fold a store to a load of a global across a store to 12 ; a parameter when the global is non-escaping. 13 ; 14 ; CHECK-LABEL: @test1( 15 ; CHECK: store i32 42, i32* @g1 16 ; CHECK-NOT: load i32 17 ; CHECK: ret i32 42 18 entry: 19 store i32 42, i32* @g1 20 store i32 7, i32* %param 21 %v = load i32, i32* @g1 22 ret i32 %v 23 } 24 25 declare i32* @f() 26 27 define i32 @test2() { 28 ; Ensure that we can fold a store to a load of a global across a store to 29 ; the pointer returned by a function call. Since the global could not escape, 30 ; this function cannot be returning its address. 31 ; 32 ; CHECK-LABEL: @test2( 33 ; CHECK: store i32 42, i32* @g1 34 ; CHECK-NOT: load i32 35 ; CHECK: ret i32 42 36 entry: 37 %ptr = call i32* @f() readnone 38 store i32 42, i32* @g1 39 store i32 7, i32* %ptr 40 %v = load i32, i32* @g1 41 ret i32 %v 42 } 43 44 @g2 = external global i32* 45 46 define i32 @test3() { 47 ; Ensure that we can fold a store to a load of a global across a store to 48 ; the pointer loaded from that global. Because the global does not escape, it 49 ; cannot alias a pointer loaded out of a global. 50 ; 51 ; CHECK-LABEL: @test3( 52 ; CHECK: store i32 42, i32* @g1 53 ; CHECK: store i32 7, i32* 54 ; CHECK-NOT: load i32 55 ; CHECK: ret i32 42 56 entry: 57 store i32 42, i32* @g1 58 %ptr1 = load i32*, i32** @g2 59 store i32 7, i32* %ptr1 60 %v = load i32, i32* @g1 61 ret i32 %v 62 } 63 64 @g3 = internal global i32 1 65 @g4 = internal global [10 x i32*] zeroinitializer 66 67 define i32 @test4(i32* %param, i32 %n, i1 %c1, i1 %c2, i1 %c3) { 68 ; Ensure that we can fold a store to a load of a global across a store to 69 ; the pointer loaded from that global even when the load is behind PHIs and 70 ; selects, and there is a mixture of a load and another global or argument. 71 ; Note that we can't eliminate the load here because it is used in a PHI and 72 ; GVN doesn't try to do real DCE. The store is still forwarded by GVN though. 73 ; 74 ; CHECK-LABEL: @test4( 75 ; CHECK: store i32 42, i32* @g1 76 ; CHECK: store i32 7, i32* 77 ; CHECK: ret i32 42 78 entry: 79 %call = call i32* @f() 80 store i32 42, i32* @g1 81 %ptr1 = load i32*, i32** @g2 82 %ptr2 = select i1 %c1, i32* %ptr1, i32* %param 83 %ptr3 = select i1 %c3, i32* %ptr2, i32* @g3 84 br label %loop 85 86 loop: 87 %iv = phi i32 [ 0, %entry ], [ %inc, %loop ] 88 %ptr = phi i32* [ %ptr3, %entry ], [ %ptr5, %loop ] 89 store i32 7, i32* %ptr 90 %ptr4 = load i32*, i32** getelementptr ([10 x i32*], [10 x i32*]* @g4, i32 0, i32 1) 91 %ptr5 = select i1 %c2, i32* %ptr4, i32* %call 92 %inc = add i32 %iv, 1 93 %test = icmp slt i32 %inc, %n 94 br i1 %test, label %loop, label %exit 95 96 exit: 97 %v = load i32, i32* @g1 98 ret i32 %v 99 } 100 101 define i32 @test5(i32** %param) { 102 ; Ensure that we can fold a store to a load of a global across a store to 103 ; a parameter that has been dereferenced when the global is non-escaping. 104 ; 105 ; CHECK-LABEL: @test5( 106 ; CHECK: %p = load i32* 107 ; CHECK: store i32 42, i32* @g1 108 ; CHECK-NOT: load i32 109 ; CHECK: ret i32 42 110 entry: 111 %p = load i32*, i32** %param 112 store i32 42, i32* @g1 113 store i32 7, i32* %p 114 %v = load i32, i32* @g1 115 ret i32 %v 116 } 117
