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llvm-mirror/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
Kyle Butt 3fc7c8cb26 CodeGen: If Convert blocks that would form a diamond when tail-merged.
The following function currently relies on tail-merging for if
conversion to succeed. The common tail of cond_true and cond_false is
extracted, and this then forms a diamond pattern that can be
successfully if converted.

If this block does not get extracted, either because tail-merging is
disabled or the threshold is higher, we should still recognize this
pattern and if-convert it.

Fixed a regression in the original commit. Need to un-reverse branches after
reversing them, or other conversions go awry.

define i32 @t2(i32 %a, i32 %b) nounwind {
entry:
        %tmp1434 = icmp eq i32 %a, %b           ; <i1> [#uses=1]
        br i1 %tmp1434, label %bb17, label %bb.outer

bb.outer:               ; preds = %cond_false, %entry
        %b_addr.021.0.ph = phi i32 [ %b, %entry ], [ %tmp10, %cond_false ]
        %a_addr.026.0.ph = phi i32 [ %a, %entry ], [ %a_addr.026.0, %cond_false ]
        br label %bb

bb:             ; preds = %cond_true, %bb.outer
        %indvar = phi i32 [ 0, %bb.outer ], [ %indvar.next, %cond_true ]
        %tmp. = sub i32 0, %b_addr.021.0.ph
        %tmp.40 = mul i32 %indvar, %tmp.
        %a_addr.026.0 = add i32 %tmp.40, %a_addr.026.0.ph
        %tmp3 = icmp sgt i32 %a_addr.026.0, %b_addr.021.0.ph
        br i1 %tmp3, label %cond_true, label %cond_false

cond_true:              ; preds = %bb
        %tmp7 = sub i32 %a_addr.026.0, %b_addr.021.0.ph
        %tmp1437 = icmp eq i32 %tmp7, %b_addr.021.0.ph
        %indvar.next = add i32 %indvar, 1
        br i1 %tmp1437, label %bb17, label %bb

cond_false:             ; preds = %bb
        %tmp10 = sub i32 %b_addr.021.0.ph, %a_addr.026.0
        %tmp14 = icmp eq i32 %a_addr.026.0, %tmp10
        br i1 %tmp14, label %bb17, label %bb.outer

bb17:           ; preds = %cond_false, %cond_true, %entry
        %a_addr.026.1 = phi i32 [ %a, %entry ], [ %tmp7, %cond_true ], [ %a_addr.026.0, %cond_false ]
        ret i32 %a_addr.026.1
}

Without tail-merging or diamond-tail if conversion:
LBB1_1:                                 @ %bb
                                        @ =>This Inner Loop Header: Depth=1
        cmp     r0, r1
        ble     LBB1_3
@ BB#2:                                 @ %cond_true
                                        @   in Loop: Header=BB1_1 Depth=1
        subs    r0, r0, r1
        cmp     r1, r0
        it      ne
        cmpne   r0, r1
        bgt     LBB1_4
LBB1_3:                                 @ %cond_false
                                        @   in Loop: Header=BB1_1 Depth=1
        subs    r1, r1, r0
        cmp     r1, r0
        bne     LBB1_1
LBB1_4:                                 @ %bb17
        bx      lr

With diamond-tail if conversion, but without tail-merging:
@ BB#0:                                 @ %entry
        cmp     r0, r1
        it      eq
        bxeq    lr
LBB1_1:                                 @ %bb
                                        @ =>This Inner Loop Header: Depth=1
        cmp     r0, r1
        ite     le
        suble   r1, r1, r0
        subgt   r0, r0, r1
        cmp     r1, r0
        bne     LBB1_1
@ BB#2:                                 @ %bb17
        bx      lr

llvm-svn: 279671
2016-08-24 21:34:27 +00:00

128 lines
4.2 KiB
LLVM

; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -arm-default-it | FileCheck %s
; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it | FileCheck %s
; RUN: llc < %s -mtriple=thumbv8 -arm-no-restrict-it -enable-tail-merge=0 | FileCheck %s
define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
; CHECK-LABEL: t1:
; CHECK: ittt ne
; CHECK: cmpne
; CHECK: addne
; CHECK: bxne lr
switch i32 %c, label %cond_next [
i32 1, label %cond_true
i32 7, label %cond_true
]
cond_true:
%tmp12 = add i32 %a, 1
%tmp1518 = add i32 %tmp12, %b
ret i32 %tmp1518
cond_next:
%tmp15 = add i32 %b, %a
ret i32 %tmp15
}
define i32 @t2(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t2:
; CHECK: ite {{gt|le}}
; CHECK-DAG: suble
; CHECK-DAG: subgt
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
bb.outer: ; preds = %cond_false, %entry
%b_addr.021.0.ph = phi i32 [ %b, %entry ], [ %tmp10, %cond_false ] ; <i32> [#uses=5]
%a_addr.026.0.ph = phi i32 [ %a, %entry ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
br label %bb
bb: ; preds = %cond_true, %bb.outer
%indvar = phi i32 [ 0, %bb.outer ], [ %indvar.next, %cond_true ] ; <i32> [#uses=2]
%tmp. = sub i32 0, %b_addr.021.0.ph ; <i32> [#uses=1]
%tmp.40 = mul i32 %indvar, %tmp. ; <i32> [#uses=1]
%a_addr.026.0 = add i32 %tmp.40, %a_addr.026.0.ph ; <i32> [#uses=6]
%tmp3 = icmp sgt i32 %a_addr.026.0, %b_addr.021.0.ph ; <i1> [#uses=1]
br i1 %tmp3, label %cond_true, label %cond_false
cond_true: ; preds = %bb
%tmp7 = sub i32 %a_addr.026.0, %b_addr.021.0.ph ; <i32> [#uses=2]
%tmp1437 = icmp eq i32 %tmp7, %b_addr.021.0.ph ; <i1> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
br i1 %tmp1437, label %bb17, label %bb
cond_false: ; preds = %bb
%tmp10 = sub i32 %b_addr.021.0.ph, %a_addr.026.0 ; <i32> [#uses=2]
%tmp14 = icmp eq i32 %a_addr.026.0, %tmp10 ; <i1> [#uses=1]
br i1 %tmp14, label %bb17, label %bb.outer
bb17: ; preds = %cond_false, %cond_true, %entry
%a_addr.026.1 = phi i32 [ %a, %entry ], [ %tmp7, %cond_true ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
ret i32 %a_addr.026.1
}
define i32 @t2_nomerge(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t2_nomerge:
; CHECK-NOT: ite {{gt|le}}
; CHECK-NOT: suble
; CHECK-NOT: subgt
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
bb.outer: ; preds = %cond_false, %entry
%b_addr.021.0.ph = phi i32 [ %b, %entry ], [ %tmp10, %cond_false ] ; <i32> [#uses=5]
%a_addr.026.0.ph = phi i32 [ %a, %entry ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
br label %bb
bb: ; preds = %cond_true, %bb.outer
%indvar = phi i32 [ 0, %bb.outer ], [ %indvar.next, %cond_true ] ; <i32> [#uses=2]
%tmp. = sub i32 0, %b_addr.021.0.ph ; <i32> [#uses=1]
%tmp.40 = mul i32 %indvar, %tmp. ; <i32> [#uses=1]
%a_addr.026.0 = add i32 %tmp.40, %a_addr.026.0.ph ; <i32> [#uses=6]
%tmp3 = icmp sgt i32 %a_addr.026.0, %b_addr.021.0.ph ; <i1> [#uses=1]
br i1 %tmp3, label %cond_true, label %cond_false
cond_true: ; preds = %bb
%tmp7 = sub i32 %a_addr.026.0, %b_addr.021.0.ph ; <i32> [#uses=2]
%tmp1437 = icmp eq i32 %tmp7, %b_addr.021.0.ph ; <i1> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
br i1 %tmp1437, label %bb17, label %bb
cond_false: ; preds = %bb
%tmp10 = sub i32 %b_addr.021.0.ph, %a_addr.026.0 ; <i32> [#uses=2]
%tmp14 = icmp eq i32 %b_addr.021.0.ph, %tmp10 ; <i1> [#uses=1]
br i1 %tmp14, label %bb17, label %bb.outer
bb17: ; preds = %cond_false, %cond_true, %entry
%a_addr.026.1 = phi i32 [ %a, %entry ], [ %tmp7, %cond_true ], [ %a_addr.026.0, %cond_false ] ; <i32> [#uses=1]
ret i32 %a_addr.026.1
}
@x = external global i32* ; <i32**> [#uses=1]
define void @foo(i32 %a) nounwind {
entry:
%tmp = load i32*, i32** @x ; <i32*> [#uses=1]
store i32 %a, i32* %tmp
ret void
}
define void @t3(i32 %a, i32 %b) nounwind {
entry:
; CHECK-LABEL: t3:
; CHECK: it lt
; CHECK-NEXT: bxlt lr
; CHECK: mov r0, r1
; CHECK: bl {{_?}}foo
%tmp1 = icmp sgt i32 %a, 10 ; <i1> [#uses=1]
br i1 %tmp1, label %cond_true, label %UnifiedReturnBlock
cond_true: ; preds = %entry
call void @foo( i32 %b )
ret void
UnifiedReturnBlock: ; preds = %entry
ret void
}