1 ; RUN: opt < %s -licm -S | FileCheck %s 2 3 @X = global i32 0 ; <i32*> [#uses=1] 4 5 declare void @foo() 6 7 ; This testcase tests for a problem where LICM hoists 8 ; potentially trapping instructions when they are not guaranteed to execute. 9 define i32 @test1(i1 %c) { 10 ; CHECK: @test1 11 %A = load i32* @X ; <i32> [#uses=2] 12 br label %Loop 13 Loop: ; preds = %LoopTail, %0 14 call void @foo( ) 15 br i1 %c, label %LoopTail, label %IfUnEqual 16 17 IfUnEqual: ; preds = %Loop 18 ; CHECK: IfUnEqual: 19 ; CHECK-NEXT: sdiv i32 4, %A 20 %B1 = sdiv i32 4, %A ; <i32> [#uses=1] 21 br label %LoopTail 22 23 LoopTail: ; preds = %IfUnEqual, %Loop 24 %B = phi i32 [ 0, %Loop ], [ %B1, %IfUnEqual ] ; <i32> [#uses=1] 25 br i1 %c, label %Loop, label %Out 26 Out: ; preds = %LoopTail 27 %C = sub i32 %A, %B ; <i32> [#uses=1] 28 ret i32 %C 29 } 30 31 32 declare void @foo2(i32) 33 34 35 ;; It is ok and desirable to hoist this potentially trapping instruction. 36 define i32 @test2(i1 %c) { 37 ; CHECK: @test2 38 ; CHECK-NEXT: load i32* @X 39 ; CHECK-NEXT: %B = sdiv i32 4, %A 40 %A = load i32* @X ; <i32> [#uses=2] 41 br label %Loop 42 Loop: 43 ;; Should have hoisted this div! 44 %B = sdiv i32 4, %A ; <i32> [#uses=2] 45 call void @foo2( i32 %B ) 46 br i1 %c, label %Loop, label %Out 47 Out: ; preds = %Loop 48 %C = sub i32 %A, %B ; <i32> [#uses=1] 49 ret i32 %C 50 } 51 52 53 ; This loop invariant instruction should be constant folded, not hoisted. 54 define i32 @test3(i1 %c) { 55 ; CHECK: define i32 @test3 56 ; CHECK: call void @foo2(i32 6) 57 %A = load i32* @X ; <i32> [#uses=2] 58 br label %Loop 59 Loop: 60 %B = add i32 4, 2 ; <i32> [#uses=2] 61 call void @foo2( i32 %B ) 62 br i1 %c, label %Loop, label %Out 63 Out: ; preds = %Loop 64 %C = sub i32 %A, %B ; <i32> [#uses=1] 65 ret i32 %C 66 } 67
