local-pre.ll
2.65 KB
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; RUN: opt < %s -gvn -enable-pre -S | FileCheck %s
; RUN: opt < %s -passes="gvn<pre>" -enable-pre=false -S | FileCheck %s
declare void @may_exit() nounwind
declare void @may_exit_1(i32) nounwind
define i32 @main(i32 %p, i32 %q) {
; CHECK-LABEL: @main(
block1:
%cmp = icmp eq i32 %p, %q
br i1 %cmp, label %block2, label %block3
block2:
%a = add i32 %p, 1
br label %block4
block3:
br label %block4
; CHECK: %.pre = add i32 %p, 1
; CHECK-NEXT: br label %block4
block4:
%b = add i32 %p, 1
ret i32 %b
; CHECK: %b.pre-phi = phi i32 [ %.pre, %block3 ], [ %a, %block2 ]
; CHECK-NEXT: ret i32 %b.pre-phi
}
; Don't PRE across implicit control flow.
define i32 @test2(i32 %p, i32 %q) {
; CHECK-LABEL: @test2
; CHECK: block1:
block1:
%cmp = icmp eq i32 %p, %q
br i1 %cmp, label %block2, label %block3
block2:
%a = sdiv i32 %p, %q
br label %block4
block3:
br label %block4
; CHECK: block4:
; CHECK-NEXT: call void @may_exit(
; CHECK-NEXT: %b = sdiv
; CHECK-NEXT: ret i32 %b
block4:
call void @may_exit() nounwind
%b = sdiv i32 %p, %q
ret i32 %b
}
; Don't PRE across implicit control flow.
define i32 @test3(i32 %p, i32 %q, i1 %r) {
; CHECK-LABEL: @test3
; CHECK: block1:
block1:
br i1 %r, label %block2, label %block3
block2:
%a = sdiv i32 %p, %q
br label %block4
block3:
br label %block4
block4:
; CHECK: block4:
; CHECK-NEXT: phi i32
; CHECK-NEXT: call void @may_exit_1(
; CHECK-NEXT: %b = sdiv
; CHECK-NEXT: ret i32 %b
%phi = phi i32 [ 0, %block3 ], [ %a, %block2 ]
call void @may_exit_1(i32 %phi) nounwind
%b = sdiv i32 %p, %q
ret i32 %b
}
; It's OK to PRE an instruction that is guaranteed to be safe to execute
; speculatively.
; TODO: Does it make any sense in this case?
define i32 @test4(i32 %p, i32 %q) {
; CHECK-LABEL: @test4
; CHECK: block1:
block1:
%cmp = icmp eq i32 %p, %q
br i1 %cmp, label %block2, label %block3
block2:
%a = sdiv i32 %p, 6
br label %block4
block3:
br label %block4
; CHECK: block4:
; CHECK-NEXT: %b.pre-phi = phi i32
; CHECK-NEXT: call void @may_exit(
; CHECK-NEXT: ret i32 %b
block4:
call void @may_exit() nounwind
%b = sdiv i32 %p, 6
ret i32 %b
}
; It is OK to PRE across implicit control flow if we don't insert new
; instructions.
define i32 @test5(i1 %cond, i32 %p, i32 %q) {
; CHECK-LABEL: @test5
; CHECK: block1:
block1:
br i1 %cond, label %block2, label %block3
block2:
%a = sdiv i32 %p, %q
br label %block4
block3:
%b = sdiv i32 %p, %q
br label %block4
; CHECK: block4:
; CHECK-NEXT: %c.pre-phi = phi i32 [ %b, %block3 ], [ %a, %block2 ]
; CHECK-NEXT: call void @may_exit()
; CHECK-NEXT: ret i32 %c.pre-phi
block4:
call void @may_exit() nounwind
%c = sdiv i32 %p, %q
ret i32 %c
}