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llvm-mirror/test/Transforms/LoopVectorize/pr38697.ll
Philip Reames db2ffb1268 [SCEV] Properly guard reasoning about infinite loops being UB on mustprogress
Noticed via code inspection. We changed the semantics of the IR when we added mustprogress, and we appear to have not updated this location.

Differential Revision: https://reviews.llvm.org/D103834
2021-06-07 14:47:36 -07:00

355 lines
14 KiB
LLVM

; RUN: opt -loop-vectorize -force-vector-width=2 -S < %s 2>&1 | FileCheck %s
; RUN: opt -indvars -S < %s 2>&1 | FileCheck %s -check-prefix=INDVARCHECK
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; Produced from test-case:
;
; void testCountIncrLoop(unsigned char *ptr, int lim, int count, int val)
; {
; int inx = 0;
; for (int outer_i = 0; outer_i < lim; ++outer_i) {
; if (count > 0) { // At runtime, 'count' is 0, so the following code is dead.
; int result = val;
; int tmp = count;
;
; while (tmp < 8) {
; result += val >> tmp;
; tmp += count;
; }
;
; ptr[inx++] = (unsigned char) result;
; }
; }
; }
;
; No explicit division appears in the input, but a division is generated during
; vectorization, and that division is a division-by-0 when the input 'count'
; is 0, so it cannot be hoisted above the guard of 'count > 0'.
; Verify that a 'udiv' does not appear in the 'loop1.preheader' block, and that
; a 'udiv' has been inserted at the top of the 'while.body.preheader' block.
define void @testCountIncrLoop(i8* %ptr, i32 %lim, i32 %count, i32 %val) mustprogress {
; CHECK-LABEL: @testCountIncrLoop(
; CHECK-NEXT: entry:
; CHECK: loop1.preheader:
; CHECK-NOT: udiv
; CHECK: loop1.body:
; CHECK: while.cond.preheader:
; CHECK: while.body.preheader:
; CHECK-NEXT: [[TMP1:%.*]] = udiv i32 [[TMP0:%.*]], [[COUNT:%.*]]
; CHECK: vector.ph:
; CHECK: exit:
; CHECK: ret void
;
entry:
%cmp1 = icmp sgt i32 %lim, 0
br i1 %cmp1, label %loop1.preheader, label %exit
loop1.preheader: ; preds = %entry
%cmp2 = icmp sgt i32 %count, 0
%cmp4 = icmp slt i32 %count, 8
br label %loop1.body
loop1.body: ; preds = %loop1.inc, %loop1.preheader
%outer_i = phi i32 [ 0, %loop1.preheader ], [ %outer_i.1, %loop1.inc ]
%inx.1 = phi i32 [ 0, %loop1.preheader ], [ %inx.2, %loop1.inc ]
br i1 %cmp2, label %while.cond.preheader, label %loop1.inc
while.cond.preheader: ; preds = %loop1.body
br i1 %cmp4, label %while.body, label %while.end
while.body: ; preds = %while.body, %while.cond.preheader
%tmp = phi i32 [ %add3, %while.body ], [ %count, %while.cond.preheader ]
%result.1 = phi i32 [ %add, %while.body ], [ %val, %while.cond.preheader ]
%shr = ashr i32 %val, %tmp
%add = add nsw i32 %shr, %result.1
%add3 = add nsw i32 %tmp, %count
%cmp3 = icmp slt i32 %add3, 8
br i1 %cmp3, label %while.body, label %while.end
while.end: ; preds = %while.body, %while.cond.preheader
%result.0.lcssa = phi i32 [ %val, %while.cond.preheader ], [ %add, %while.body ]
%conv = trunc i32 %result.0.lcssa to i8
%inc = add nsw i32 %inx.1, 1
%idxprom = sext i32 %inx.1 to i64
%arrayidx = getelementptr inbounds i8, i8* %ptr, i64 %idxprom
store i8 %conv, i8* %arrayidx, align 1
br label %loop1.inc
loop1.inc: ; preds = %while.end, %loop1.body
%inx.2 = phi i32 [ %inc, %while.end ], [ %inx.1, %loop1.body ]
%outer_i.1 = add nuw nsw i32 %outer_i, 1
%exitcond = icmp eq i32 %outer_i.1, %lim
br i1 %exitcond, label %exit, label %loop1.body
exit: ; preds = %loop1.inc, %entry
ret void
}
; These next tests are all based on the following source code, with slight
; variations on the calculation of 'incr' (all of which are loop-invariant
; divisions, but only some of which can be safely hoisted):
;
; uint32_t foo(uint32_t *ptr, uint32_t start1, uint32_t start2) {
; uint32_t counter1, counter2;
; uint32_t val = start1;
; for (counter1 = 1; counter1 < 100; ++counter1) {
; uint32_t index = 0;
; val += ptr[index];
; for (counter2 = start2; counter2 < 10; ++counter2) {
; // Division is loop invariant, and denominator is guaranteed non-zero:
; // Safe to hoist it out of the inner loop.
; uint32_t incr = 16 / counter1;
; index += incr;
; val += ptr[index];
; }
; }
; return val;
; }
; This version is as written above, where 'incr' is '16/counter1', and it is
; guaranted that 'counter1' is always non-zero. So it is safe to hoist the
; division from the inner loop to the preheader.
;
; Verify that the 'udiv' is hoisted to the preheader, and is not in the loop body.
define i32 @NonZeroDivHoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
; INDVARCHECK-LABEL: @NonZeroDivHoist(
; INDVARCHECK-NEXT: entry:
; INDVARCHECK: for.body3.lr.ph:
; INDVARCHECK-NEXT: [[TMP0:%.*]] = udiv i64 16, [[INDVARS_IV:%.*]]
; INDVARCHECK-NEXT: br label [[FOR_BODY3:%.*]]
; INDVARCHECK: for.body3:
; INDVARCHECK-NOT: udiv
; INDVARCHECK: for.end10:
;
entry:
br label %for.cond
for.cond: ; preds = %for.end, %entry
%val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
%counter1.0 = phi i32 [ 1, %entry ], [ %inc9, %for.end ]
%cmp = icmp ult i32 %counter1.0, 100
br i1 %cmp, label %for.body, label %for.end10
for.body: ; preds = %for.cond
%tmp = load i32, i32* %ptr, align 4
%add = add i32 %tmp, %val.0
%cmp224 = icmp ult i32 %start2, 10
br i1 %cmp224, label %for.body3.lr.ph, label %for.end
for.body3.lr.ph: ; preds = %for.body
br label %for.body3
for.body3: ; preds = %for.body3, %for.body3.lr.ph
%index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
%val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
%counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
%div = udiv i32 16, %counter1.0
%add4 = add i32 %div, %index.027
%idxprom5 = zext i32 %add4 to i64
%arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
%tmp1 = load i32, i32* %arrayidx6, align 4
%add7 = add i32 %tmp1, %val.126
%inc = add i32 %counter2.025, 1
%cmp2 = icmp ult i32 %inc, 10
br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
for.cond1.for.end_crit_edge: ; preds = %for.body3
%split = phi i32 [ %add7, %for.body3 ]
br label %for.end
for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
%val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
%inc9 = add i32 %counter1.0, 1
br label %for.cond
for.end10: ; preds = %for.cond
%val.0.lcssa = phi i32 [ %val.0, %for.cond ]
ret i32 %val.0.lcssa
}
; This version is identical to the above 'NonZeroDivHoist' case, except the
; outer ('counter1') loop starts at the unknown value of 'start1' rather than 1,
; and so it is illegal to hoist the division because if 'start1' is 0, hoisting
; it would incorrectly cause a divide-by-zero trap.
;
; Verify that the 'udiv' is not hoisted to the preheader, and it remains in the
; loop body.
define i32 @ZeroDivNoHoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
; INDVARCHECK-LABEL: @ZeroDivNoHoist(
; INDVARCHECK-NEXT: entry:
; INDVARCHECK-NOT: udiv
; INDVARCHECK: for.body3:
; INDVARCHECK: [[TMP1:%.*]] = udiv i64 16, [[INDVARS_IV:%.*]]
; INDVARCHECK: for.cond1.for.end_crit_edge:
;
entry:
br label %for.cond
for.cond: ; preds = %for.end, %entry
%val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
%counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
%cmp = icmp ult i32 %counter1.0, 100
br i1 %cmp, label %for.body, label %for.end10
for.body: ; preds = %for.cond
%tmp = load i32, i32* %ptr, align 4
%add = add i32 %tmp, %val.0
%cmp224 = icmp ult i32 %start2, 10
br i1 %cmp224, label %for.body3.lr.ph, label %for.end
for.body3.lr.ph: ; preds = %for.body
br label %for.body3
for.body3: ; preds = %for.body3, %for.body3.lr.ph
%index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
%val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
%counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
%div = udiv i32 16, %counter1.0
%add4 = add i32 %div, %index.027
%idxprom5 = zext i32 %add4 to i64
%arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
%tmp1 = load i32, i32* %arrayidx6, align 4
%add7 = add i32 %tmp1, %val.126
%inc = add i32 %counter2.025, 1
%cmp2 = icmp ult i32 %inc, 10
br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
for.cond1.for.end_crit_edge: ; preds = %for.body3
%split = phi i32 [ %add7, %for.body3 ]
br label %for.end
for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
%val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
%inc9 = add i32 %counter1.0, 1
br label %for.cond
for.end10: ; preds = %for.cond
%val.0.lcssa = phi i32 [ %val.0, %for.cond ]
ret i32 %val.0.lcssa
}
; This version is has a clearly safe division by a non-zero constant (16). The
; division is transformed to a logical-shift-right of 4, and it is safely
; hoisted.
;
; Verify that the division-operation is hoisted, and that it appears as a
; right-shift ('lshr') rather than an explicit division.
define i32 @DivBy16Hoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
; INDVARCHECK-LABEL: @DivBy16Hoist(
; INDVARCHECK-NEXT: entry:
; INDVARCHECK: for.cond:
; INDVARCHECK: [[TMP1:%.*]] = lshr i64 [[INDVARS_IV:%.*]], 4
; INDVARCHECK: for.body:
; INDVARCHECK-NOT: lshr
; INDVARCHECK-NOT: udiv
; INDVARCHECK: for.end10:
;
entry:
br label %for.cond
for.cond: ; preds = %for.end, %entry
%val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
%counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
%cmp = icmp ult i32 %counter1.0, 100
br i1 %cmp, label %for.body, label %for.end10
for.body: ; preds = %for.cond
%tmp = load i32, i32* %ptr, align 4
%add = add i32 %tmp, %val.0
%cmp224 = icmp ult i32 %start2, 10
br i1 %cmp224, label %for.body3.lr.ph, label %for.end
for.body3.lr.ph: ; preds = %for.body
br label %for.body3
for.body3: ; preds = %for.body3, %for.body3.lr.ph
%index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
%val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
%counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
%div = udiv i32 %counter1.0, 16
%add4 = add i32 %div, %index.027
%idxprom5 = zext i32 %add4 to i64
%arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
%tmp1 = load i32, i32* %arrayidx6, align 4
%add7 = add i32 %tmp1, %val.126
%inc = add i32 %counter2.025, 1
%cmp2 = icmp ult i32 %inc, 10
br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
for.cond1.for.end_crit_edge: ; preds = %for.body3
%split = phi i32 [ %add7, %for.body3 ]
br label %for.end
for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
%val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
%inc9 = add i32 %counter1.0, 1
br label %for.cond
for.end10: ; preds = %for.cond
%val.0.lcssa = phi i32 [ %val.0, %for.cond ]
ret i32 %val.0.lcssa
}
; This version is has a clearly safe division by a non-zero constant (17). The
; division is safely hoisted, as it was in the 'DivBy16Hoist' verison, but here
; it remains a division, rather than being transformed to a right-shift.
;
; Verify that the division-operation is hoisted.
define i32 @DivBy17Hoist(i32* nocapture readonly %ptr, i32 %start1, i32 %start2) {
; INDVARCHECK-LABEL: @DivBy17Hoist(
; INDVARCHECK-NEXT: entry:
; INDVARCHECK: for.cond:
; INDVARCHECK: [[TMP1:%.*]] = udiv i64 [[INDVARS_IV:%.*]], 17
; INDVARCHECK: for.body:
; INDVARCHECK-NOT: udiv
; INDVARCHECK: for.end10:
;
entry:
br label %for.cond
for.cond: ; preds = %for.end, %entry
%val.0 = phi i32 [ %start1, %entry ], [ %val.1.lcssa, %for.end ]
%counter1.0 = phi i32 [ %start1, %entry ], [ %inc9, %for.end ]
%cmp = icmp ult i32 %counter1.0, 100
br i1 %cmp, label %for.body, label %for.end10
for.body: ; preds = %for.cond
%tmp = load i32, i32* %ptr, align 4
%add = add i32 %tmp, %val.0
%cmp224 = icmp ult i32 %start2, 10
br i1 %cmp224, label %for.body3.lr.ph, label %for.end
for.body3.lr.ph: ; preds = %for.body
br label %for.body3
for.body3: ; preds = %for.body3, %for.body3.lr.ph
%index.027 = phi i32 [ 0, %for.body3.lr.ph ], [ %add4, %for.body3 ]
%val.126 = phi i32 [ %add, %for.body3.lr.ph ], [ %add7, %for.body3 ]
%counter2.025 = phi i32 [ %start2, %for.body3.lr.ph ], [ %inc, %for.body3 ]
%div = udiv i32 %counter1.0, 17
%add4 = add i32 %div, %index.027
%idxprom5 = zext i32 %add4 to i64
%arrayidx6 = getelementptr inbounds i32, i32* %ptr, i64 %idxprom5
%tmp1 = load i32, i32* %arrayidx6, align 4
%add7 = add i32 %tmp1, %val.126
%inc = add i32 %counter2.025, 1
%cmp2 = icmp ult i32 %inc, 10
br i1 %cmp2, label %for.body3, label %for.cond1.for.end_crit_edge
for.cond1.for.end_crit_edge: ; preds = %for.body3
%split = phi i32 [ %add7, %for.body3 ]
br label %for.end
for.end: ; preds = %for.cond1.for.end_crit_edge, %for.body
%val.1.lcssa = phi i32 [ %split, %for.cond1.for.end_crit_edge ], [ %add, %for.body ]
%inc9 = add i32 %counter1.0, 1
br label %for.cond
for.end10: ; preds = %for.cond
%val.0.lcssa = phi i32 [ %val.0, %for.cond ]
ret i32 %val.0.lcssa
}