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llvm-mirror/test/Transforms/GVN/edge.ll
Rafael Espindola d7ec990084 Teach GVN to reason about edges dominating uses. This allows it to handle cases
where some fact lake a=b dominates a use in a phi, but doesn't dominate the
basic block itself.

This feature could also be implemented by splitting critical edges, but at least
with the current algorithm reasoning about the dominance directly is faster.

The time for running "opt -O2" in the testcase in pr10584 is 1.003 times slower
and on gcc as a single file it is 1.0007 times faster.

llvm-svn: 162023
2012-08-16 15:09:43 +00:00

61 lines
1.1 KiB
LLVM

; RUN: opt %s -gvn -S -o - | FileCheck %s
define i32 @f1(i32 %x) {
; CHECK: define i32 @f1(
bb0:
%cmp = icmp eq i32 %x, 0
br i1 %cmp, label %bb2, label %bb1
bb1:
br label %bb2
bb2:
%cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
%foo = add i32 %cond, %x
ret i32 %foo
; CHECK: bb2:
; CHECK: ret i32 %x
}
define i32 @f2(i32 %x) {
; CHECK: define i32 @f2(
bb0:
%cmp = icmp ne i32 %x, 0
br i1 %cmp, label %bb1, label %bb2
bb1:
br label %bb2
bb2:
%cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
%foo = add i32 %cond, %x
ret i32 %foo
; CHECK: bb2:
; CHECK: ret i32 %x
}
define i32 @f3(i32 %x) {
; CHECK: define i32 @f3(
bb0:
switch i32 %x, label %bb1 [ i32 0, label %bb2]
bb1:
br label %bb2
bb2:
%cond = phi i32 [ %x, %bb0 ], [ 0, %bb1 ]
%foo = add i32 %cond, %x
ret i32 %foo
; CHECK: bb2:
; CHECK: ret i32 %x
}
declare void @g(i1)
define void @f4(i8 * %x) {
; CHECK: define void @f4(
bb0:
%y = icmp eq i8* null, %x
br i1 %y, label %bb2, label %bb1
bb1:
br label %bb2
bb2:
%zed = icmp eq i8* null, %x
call void @g(i1 %zed)
; CHECK: call void @g(i1 %y)
ret void
}