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llvm-mirror/test/Transforms/LoopVectorize/pr44488-predication.ll
Sjoerd Meijer cc03ee5234 Recommit #2: "[LV] Induction Variable does not remain scalar under tail-folding."
This was reverted because of a miscompilation. At closer inspection, the
problem was actually visible in a changed llvm regression test too. This
one-line follow up fix/recommit will splat the IV, which is what we are trying
to avoid if unnecessary in general, if tail-folding is requested even if all
users are scalar instructions after vectorisation. Because with tail-folding,
the splat IV will be used by the predicate of the masked loads/stores
instructions. The previous version omitted this, which caused the
miscompilation. The original commit message was:

If tail-folding of the scalar remainder loop is applied, the primary induction
variable is splat to a vector and used by the masked load/store vector
instructions, thus the IV does not remain scalar. Because we now mark
that the IV does not remain scalar for these cases, we don't emit the vector IV
if it is not used. Thus, the vectoriser produces less dead code.

Thanks to Ayal Zaks for the direction how to fix this.
2020-05-13 13:50:09 +01:00

111 lines
5.8 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -S | FileCheck %s
; Test case for PR44488. Checks that the correct predicates are created for
; branches where true and false successors are equal. See the checks involving
; CMP1 and CMP2.
@v_38 = global i16 12061, align 1
@v_39 = global i16 11333, align 1
define i16 @test_true_and_false_branch_equal() {
; CHECK-LABEL: @test_true_and_false_branch_equal(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[PRED_SREM_CONTINUE2:%.*]] ]
; CHECK-NEXT: [[TMP0:%.*]] = trunc i32 [[INDEX]] to i16
; CHECK-NEXT: [[OFFSET_IDX:%.*]] = add i16 99, [[TMP0]]
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <2 x i16> undef, i16 [[OFFSET_IDX]], i32 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <2 x i16> [[BROADCAST_SPLATINSERT]], <2 x i16> undef, <2 x i32> zeroinitializer
; CHECK-NEXT: [[INDUCTION:%.*]] = add <2 x i16> [[BROADCAST_SPLAT]], <i16 0, i16 1>
; CHECK-NEXT: [[TMP1:%.*]] = add i16 [[OFFSET_IDX]], 0
; CHECK-NEXT: [[TMP2:%.*]] = load i16, i16* @v_38, align 1
; CHECK-NEXT: [[TMP3:%.*]] = load i16, i16* @v_38, align 1
; CHECK-NEXT: [[TMP4:%.*]] = insertelement <2 x i16> undef, i16 [[TMP2]], i32 0
; CHECK-NEXT: [[TMP5:%.*]] = insertelement <2 x i16> [[TMP4]], i16 [[TMP3]], i32 1
; CHECK-NEXT: [[TMP6:%.*]] = icmp eq <2 x i16> [[TMP5]], <i16 32767, i16 32767>
; CHECK-NEXT: [[TMP7:%.*]] = icmp eq <2 x i16> [[TMP5]], zeroinitializer
; CHECK-NEXT: [[TMP8:%.*]] = xor <2 x i1> [[TMP7]], <i1 true, i1 true>
; CHECK-NEXT: [[TMP9:%.*]] = extractelement <2 x i1> [[TMP8]], i32 0
; CHECK-NEXT: br i1 [[TMP9]], label [[PRED_SREM_IF:%.*]], label [[PRED_SREM_CONTINUE:%.*]]
; CHECK: pred.srem.if:
; CHECK-NEXT: [[TMP10:%.*]] = srem i16 5786, [[TMP2]]
; CHECK-NEXT: [[TMP11:%.*]] = insertelement <2 x i16> undef, i16 [[TMP10]], i32 0
; CHECK-NEXT: br label [[PRED_SREM_CONTINUE]]
; CHECK: pred.srem.continue:
; CHECK-NEXT: [[TMP12:%.*]] = phi <2 x i16> [ undef, [[VECTOR_BODY]] ], [ [[TMP11]], [[PRED_SREM_IF]] ]
; CHECK-NEXT: [[TMP13:%.*]] = extractelement <2 x i1> [[TMP8]], i32 1
; CHECK-NEXT: br i1 [[TMP13]], label [[PRED_SREM_IF1:%.*]], label [[PRED_SREM_CONTINUE2]]
; CHECK: pred.srem.if1:
; CHECK-NEXT: [[TMP14:%.*]] = srem i16 5786, [[TMP3]]
; CHECK-NEXT: [[TMP15:%.*]] = insertelement <2 x i16> [[TMP12]], i16 [[TMP14]], i32 1
; CHECK-NEXT: br label [[PRED_SREM_CONTINUE2]]
; CHECK: pred.srem.continue2:
; CHECK-NEXT: [[TMP16:%.*]] = phi <2 x i16> [ [[TMP12]], [[PRED_SREM_CONTINUE]] ], [ [[TMP15]], [[PRED_SREM_IF1]] ]
; CHECK-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP7]], <2 x i16> <i16 5786, i16 5786>, <2 x i16> [[TMP16]]
; CHECK-NEXT: [[TMP17:%.*]] = extractelement <2 x i16> [[PREDPHI]], i32 0
; CHECK-NEXT: store i16 [[TMP17]], i16* @v_39, align 1
; CHECK-NEXT: [[TMP18:%.*]] = extractelement <2 x i16> [[PREDPHI]], i32 1
; CHECK-NEXT: store i16 [[TMP18]], i16* @v_39, align 1
; CHECK-NEXT: [[INDEX_NEXT]] = add i32 [[INDEX]], 2
; CHECK-NEXT: [[TMP19:%.*]] = icmp eq i32 [[INDEX_NEXT]], 12
; CHECK-NEXT: br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop !0
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 12, 12
; CHECK-NEXT: br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i16 [ 111, [[MIDDLE_BLOCK]] ], [ 99, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[I_07:%.*]] = phi i16 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC7:%.*]], [[FOR_LATCH:%.*]] ]
; CHECK-NEXT: [[LV:%.*]] = load i16, i16* @v_38, align 1
; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i16 [[LV]], 32767
; CHECK-NEXT: br i1 [[CMP1]], label [[COND_END:%.*]], label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i16 [[LV]], 0
; CHECK-NEXT: br i1 [[CMP2]], label [[FOR_LATCH]], label [[COND_FALSE4:%.*]]
; CHECK: cond.false4:
; CHECK-NEXT: [[REM:%.*]] = srem i16 5786, [[LV]]
; CHECK-NEXT: br label [[FOR_LATCH]]
; CHECK: for.latch:
; CHECK-NEXT: [[COND6:%.*]] = phi i16 [ [[REM]], [[COND_FALSE4]] ], [ 5786, [[COND_END]] ]
; CHECK-NEXT: store i16 [[COND6]], i16* @v_39, align 1
; CHECK-NEXT: [[INC7]] = add nsw i16 [[I_07]], 1
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i16 [[INC7]], 111
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[EXIT]], !llvm.loop !2
; CHECK: exit:
; CHECK-NEXT: [[RV:%.*]] = load i16, i16* @v_39, align 1
; CHECK-NEXT: ret i16 [[RV]]
;
entry:
br label %for.body
for.body: ; preds = %entry, %for.latch
%i.07 = phi i16 [ 99, %entry ], [ %inc7, %for.latch ]
%lv = load i16, i16* @v_38, align 1
%cmp1 = icmp eq i16 %lv, 32767
br i1 %cmp1, label %cond.end, label %cond.end
cond.end: ; preds = %for.body, %for.body
%cmp2 = icmp eq i16 %lv, 0
br i1 %cmp2, label %for.latch, label %cond.false4
cond.false4: ; preds = %cond.end
%rem = srem i16 5786, %lv
br label %for.latch
for.latch: ; preds = %cond.end, %cond.false4
%cond6 = phi i16 [ %rem, %cond.false4 ], [ 5786, %cond.end ]
store i16 %cond6, i16* @v_39, align 1
%inc7 = add nsw i16 %i.07, 1
%cmp = icmp slt i16 %inc7, 111
br i1 %cmp, label %for.body, label %exit
exit: ; preds = %for.latch
%rv = load i16, i16* @v_39, align 1
ret i16 %rv
}