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llvm-mirror/test/CodeGen/X86/loop-strength-reduce5.ll
Evan Cheng 53696b7e9f Loosen up iv reuse to allow reuse of the same stride but a larger type when truncating from the larger type to smaller type is free.
e.g.
Turns this loop:
LBB1_1: # entry.bb_crit_edge
        xorl    %ecx, %ecx
        xorw    %dx, %dx
        movw    %dx, %si
LBB1_2: # bb
        movl    L_X$non_lazy_ptr, %edi
        movw    %si, (%edi)
        movl    L_Y$non_lazy_ptr, %edi
        movw    %dx, (%edi)
		addw    $4, %dx
		incw    %si
		incl    %ecx
		cmpl    %eax, %ecx
		jne     LBB1_2  # bb
	
into

LBB1_1: # entry.bb_crit_edge
        xorl    %ecx, %ecx
        xorw    %dx, %dx
LBB1_2: # bb
        movl    L_X$non_lazy_ptr, %esi
        movw    %cx, (%esi)
        movl    L_Y$non_lazy_ptr, %esi
        movw    %dx, (%esi)
        addw    $4, %dx
		incl    %ecx
        cmpl    %eax, %ecx
        jne     LBB1_2  # bb

llvm-svn: 43375
2007-10-26 01:56:11 +00:00

24 lines
766 B
LLVM

; RUN: llvm-as < %s | llc -march=x86 | grep inc | count 1
@X = weak global i16 0 ; <i16*> [#uses=1]
@Y = weak global i16 0 ; <i16*> [#uses=1]
define void @foo(i32 %N) {
entry:
%tmp1019 = icmp sgt i32 %N, 0 ; <i1> [#uses=1]
br i1 %tmp1019, label %bb, label %return
bb: ; preds = %bb, %entry
%i.014.0 = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
%tmp1 = trunc i32 %i.014.0 to i16 ; <i16> [#uses=2]
volatile store i16 %tmp1, i16* @X, align 2
%tmp34 = shl i16 %tmp1, 2 ; <i16> [#uses=1]
volatile store i16 %tmp34, i16* @Y, align 2
%indvar.next = add i32 %i.014.0, 1 ; <i32> [#uses=2]
%exitcond = icmp eq i32 %indvar.next, %N ; <i1> [#uses=1]
br i1 %exitcond, label %return, label %bb
return: ; preds = %bb, %entry
ret void
}