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llvm-mirror/test/CodeGen/X86/loop-strength-reduce4.ll
Evan Cheng 66cbf54030 If a loop termination compare instruction is the only use of its stride,
and the compaison is against a constant value, try eliminate the stride
by moving the compare instruction to another stride and change its
constant operand accordingly. e.g.

loop:
...
v1 = v1 + 3
v2 = v2 + 1
if (v2 < 10) goto loop
=>
loop:
...
v1 = v1 + 3
if (v1 < 30) goto loop

llvm-svn: 43336
2007-10-25 09:11:16 +00:00

50 lines
2.3 KiB
LLVM

; RUN: llvm-as < %s | llc -march=x86 | grep cmp | grep 64
; RUN: llvm-as < %s | llc -march=x86 | not grep inc
@state = external global [0 x i32] ; <[0 x i32]*> [#uses=4]
@S = external global [0 x i32] ; <[0 x i32]*> [#uses=4]
define i32 @foo() {
entry:
br label %bb
bb: ; preds = %bb, %entry
%indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
%t.063.0 = phi i32 [ 0, %entry ], [ %tmp47, %bb ] ; <i32> [#uses=1]
%j.065.0 = shl i32 %indvar, 2 ; <i32> [#uses=4]
%tmp3 = getelementptr [0 x i32]* @state, i32 0, i32 %j.065.0 ; <i32*> [#uses=2]
%tmp4 = load i32* %tmp3, align 4 ; <i32> [#uses=1]
%tmp6 = getelementptr [0 x i32]* @S, i32 0, i32 %t.063.0 ; <i32*> [#uses=1]
%tmp7 = load i32* %tmp6, align 4 ; <i32> [#uses=1]
%tmp8 = xor i32 %tmp7, %tmp4 ; <i32> [#uses=2]
store i32 %tmp8, i32* %tmp3, align 4
%tmp1378 = or i32 %j.065.0, 1 ; <i32> [#uses=1]
%tmp16 = getelementptr [0 x i32]* @state, i32 0, i32 %tmp1378 ; <i32*> [#uses=2]
%tmp17 = load i32* %tmp16, align 4 ; <i32> [#uses=1]
%tmp19 = getelementptr [0 x i32]* @S, i32 0, i32 %tmp8 ; <i32*> [#uses=1]
%tmp20 = load i32* %tmp19, align 4 ; <i32> [#uses=1]
%tmp21 = xor i32 %tmp20, %tmp17 ; <i32> [#uses=2]
store i32 %tmp21, i32* %tmp16, align 4
%tmp2680 = or i32 %j.065.0, 2 ; <i32> [#uses=1]
%tmp29 = getelementptr [0 x i32]* @state, i32 0, i32 %tmp2680 ; <i32*> [#uses=2]
%tmp30 = load i32* %tmp29, align 4 ; <i32> [#uses=1]
%tmp32 = getelementptr [0 x i32]* @S, i32 0, i32 %tmp21 ; <i32*> [#uses=1]
%tmp33 = load i32* %tmp32, align 4 ; <i32> [#uses=1]
%tmp34 = xor i32 %tmp33, %tmp30 ; <i32> [#uses=2]
store i32 %tmp34, i32* %tmp29, align 4
%tmp3982 = or i32 %j.065.0, 3 ; <i32> [#uses=1]
%tmp42 = getelementptr [0 x i32]* @state, i32 0, i32 %tmp3982 ; <i32*> [#uses=2]
%tmp43 = load i32* %tmp42, align 4 ; <i32> [#uses=1]
%tmp45 = getelementptr [0 x i32]* @S, i32 0, i32 %tmp34 ; <i32*> [#uses=1]
%tmp46 = load i32* %tmp45, align 4 ; <i32> [#uses=1]
%tmp47 = xor i32 %tmp46, %tmp43 ; <i32> [#uses=3]
store i32 %tmp47, i32* %tmp42, align 4
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
%exitcond = icmp eq i32 %indvar.next, 4 ; <i1> [#uses=1]
br i1 %exitcond, label %bb57, label %bb
bb57: ; preds = %bb
%tmp59 = and i32 %tmp47, 255 ; <i32> [#uses=1]
ret i32 %tmp59
}