; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s
; ScalarEvolution should be able to understand the loop and eliminate the casts.
; CHECK: {%d,+,4}
define void @foo(i32* nocapture %d, i32 %n) nounwind {
entry:
%0 = icmp sgt i32 %n, 0 ; <i1> [#uses=1]
br i1 %0, label %bb.nph, label %return
bb.nph: ; preds = %entry
br label %bb
bb: ; preds = %bb1, %bb.nph
%i.02 = phi i32 [ %5, %bb1 ], [ 0, %bb.nph ] ; <i32> [#uses=2]
%p.01 = phi i8 [ %4, %bb1 ], [ -1, %bb.nph ] ; <i8> [#uses=2]
%1 = sext i8 %p.01 to i32 ; <i32> [#uses=1]
%2 = sext i32 %i.02 to i64 ; <i64> [#uses=1]
%3 = getelementptr i32, i32* %d, i64 %2 ; <i32*> [#uses=1]
store i32 %1, i32* %3, align 4
%4 = add i8 %p.01, 1 ; <i8> [#uses=1]
%5 = add i32 %i.02, 1 ; <i32> [#uses=2]
br label %bb1
bb1: ; preds = %bb
%6 = icmp slt i32 %5, %n ; <i1> [#uses=1]
br i1 %6, label %bb, label %bb1.return_crit_edge
bb1.return_crit_edge: ; preds = %bb1
br label %return
return: ; preds = %bb1.return_crit_edge, %entry
ret void
}
; ScalarEvolution should be able to find the maximum tripcount
; of this multiple-exit loop, and if it doesn't know the exact
; count, it should say so.
; PR7845
; CHECK: Loop %for.cond: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.cond: max backedge-taken count is 5
@.str = private constant [4 x i8] c"%d\0A\00" ; <[4 x i8]*> [#uses=2]
define i32 @main() nounwind {
entry:
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%g_4.0 = phi i32 [ 0, %entry ], [ %add, %for.inc ] ; <i32> [#uses=5]
%cmp = icmp slt i32 %g_4.0, 5 ; <i1> [#uses=1]
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%conv = trunc i32 %g_4.0 to i16 ; <i16> [#uses=1]
%tobool.not = icmp eq i16 %conv, 0 ; <i1> [#uses=1]
%tobool3 = icmp ne i32 %g_4.0, 0 ; <i1> [#uses=1]
%or.cond = and i1 %tobool.not, %tobool3 ; <i1> [#uses=1]
br i1 %or.cond, label %for.end, label %for.inc
for.inc: ; preds = %for.body
%add = add nsw i32 %g_4.0, 1 ; <i32> [#uses=1]
br label %for.cond
for.end: ; preds = %for.body, %for.cond
%call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i32 %g_4.0) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @printf(i8*, ...)
define void @test(i8* %a, i32 %n) nounwind {
entry:
%cmp1 = icmp sgt i32 %n, 0
br i1 %cmp1, label %for.body.lr.ph, label %for.end
for.body.lr.ph: ; preds = %entry
%tmp = zext i32 %n to i64
br label %for.body
for.body: ; preds = %for.body, %for.body.lr.ph
%indvar = phi i64 [ %indvar.next, %for.body ], [ 0, %for.body.lr.ph ]
%arrayidx = getelementptr i8, i8* %a, i64 %indvar
store i8 0, i8* %arrayidx, align 1
%indvar.next = add i64 %indvar, 1
%exitcond = icmp ne i64 %indvar.next, %tmp
br i1 %exitcond, label %for.body, label %for.cond.for.end_crit_edge
for.cond.for.end_crit_edge: ; preds = %for.body
br label %for.end
for.end: ; preds = %for.cond.for.end_crit_edge, %entry
ret void
}
; CHECK: Determining loop execution counts for: @test
; CHECK-NEXT: backedge-taken count is
; CHECK-NEXT: max backedge-taken count is 2147483646
; PR19799: Indvars miscompile due to an incorrect max backedge taken count from SCEV.
; CHECK-LABEL: @pr19799
; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body.i: max backedge-taken count is 1
@a = common global i32 0, align 4
define i32 @pr19799() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp eq i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%cmp.i = icmp slt i32 %storemerge1.i, 0
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; PR18886: Indvars miscompile due to an incorrect max backedge taken count from SCEV.
; CHECK-LABEL: @pr18886
; CHECK: Loop %for.body: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body: max backedge-taken count is 3
@aa = global i64 0, align 8
define i32 @pr18886() {
entry:
store i64 -21, i64* @aa, align 8
br label %for.body
for.body:
%storemerge1 = phi i64 [ -21, %entry ], [ %add, %for.cond ]
%tobool = icmp eq i64 %storemerge1, 0
%add = add nsw i64 %storemerge1, 8
br i1 %tobool, label %return, label %for.cond
for.cond:
store i64 %add, i64* @aa, align 8
%cmp = icmp slt i64 %add, 9
br i1 %cmp, label %for.body, label %return
return:
%retval.0 = phi i32 [ 1, %for.body ], [ 0, %for.cond ]
ret i32 %retval.0
}
; Here we have a must-exit loop latch that is not computable and a
; may-exit early exit that can only have one non-exiting iteration
; before the check is forever skipped.
;
; CHECK-LABEL: @cannot_compute_mustexit
; CHECK: Loop %for.body.i: <multiple exits> Unpredictable backedge-taken count.
; CHECK: Loop %for.body.i: Unpredictable max backedge-taken count.
@b = common global i32 0, align 4
define i32 @cannot_compute_mustexit() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp eq i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%ld = load volatile i32, i32* @b
%cmp.i = icmp ne i32 %ld, 0
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; This loop has two must-exits, both of which dominate the latch. The
; MaxBECount should be the minimum of them.
;
; CHECK-LABEL: @two_mustexit
; CHECK: Loop %for.body.i: <multiple exits> backedge-taken count is 1
; CHECK: Loop %for.body.i: max backedge-taken count is 1
define i32 @two_mustexit() {
entry:
store i32 -1, i32* @a, align 4
br label %for.body.i
for.body.i: ; preds = %for.cond.i, %entry
%storemerge1.i = phi i32 [ -1, %entry ], [ %add.i.i, %for.cond.i ]
%tobool.i = icmp sgt i32 %storemerge1.i, 0
%add.i.i = add nsw i32 %storemerge1.i, 2
br i1 %tobool.i, label %bar.exit, label %for.cond.i
for.cond.i: ; preds = %for.body.i
store i32 %add.i.i, i32* @a, align 4
%cmp.i = icmp slt i32 %storemerge1.i, 3
br i1 %cmp.i, label %for.body.i, label %bar.exit
bar.exit: ; preds = %for.cond.i, %for.body.i
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_1
; CHECK: Loop %for.body: max backedge-taken count is 7
define i32 @ne_max_trip_count_1(i32 %n) {
entry:
%masked = and i32 %n, 7
br label %for.body
for.body:
%i = phi i32 [ 0, %entry ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %i, %masked
br i1 %cmp, label %for.body, label %bar.exit
bar.exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_2
; CHECK: Loop %for.body: max backedge-taken count is -1
define i32 @ne_max_trip_count_2(i32 %n) {
entry:
%masked = and i32 %n, 7
br label %for.body
for.body:
%i = phi i32 [ 0, %entry ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %masked
br i1 %cmp, label %for.body, label %bar.exit
bar.exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_3
; CHECK: Loop %for.body: max backedge-taken count is 6
define i32 @ne_max_trip_count_3(i32 %n) {
entry:
%masked = and i32 %n, 7
%guard = icmp eq i32 %masked, 0
br i1 %guard, label %exit, label %for.preheader
for.preheader:
br label %for.body
for.body:
%i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %masked
br i1 %cmp, label %for.body, label %loop.exit
loop.exit:
br label %exit
exit:
ret i32 0
}
; CHECK-LABEL: @ne_max_trip_count_4
; CHECK: Loop %for.body: max backedge-taken count is -2
define i32 @ne_max_trip_count_4(i32 %n) {
entry:
%guard = icmp eq i32 %n, 0
br i1 %guard, label %exit, label %for.preheader
for.preheader:
br label %for.body
for.body:
%i = phi i32 [ 0, %for.preheader ], [ %add, %for.body ]
%add = add nsw i32 %i, 1
%cmp = icmp ne i32 %add, %n
br i1 %cmp, label %for.body, label %loop.exit
loop.exit:
br label %exit
exit:
ret i32 0
}
; The end bound of the loop can change between iterations, so the exact trip
; count is unknown, but SCEV can calculate the max trip count.
define void @changing_end_bound(i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: max backedge-taken count is 2147483646
entry:
br label %loop
loop:
%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add nsw i32 %iv, 1
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; Similar test as above, but unknown start value.
; Also, there's no nsw on the iv.next, but SCEV knows
; the termination condition is LT, so the IV cannot wrap.
define void @changing_end_bound2(i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound2
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: max backedge-taken count is -1
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add i32 %iv, 1
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; changing end bound and greater than one stride
define void @changing_end_bound3(i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound3
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: max backedge-taken count is 1073741823
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add nsw i32 %iv, 4
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; same as above test, but the IV can wrap around.
; so the max backedge taken count is unpredictable.
define void @changing_end_bound4(i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound4
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add i32 %iv, 4
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; unknown stride. Since it's not knownPositive, we do not estimate the max
; backedge taken count.
define void @changing_end_bound5(i32 %stride, i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound5
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add nsw i32 %iv, %stride
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; negative stride value
define void @changing_end_bound6(i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound6
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add nsw i32 %iv, -1
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp slt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
; sgt with negative stride
define void @changing_end_bound7(i32 %start, i32* %n_addr, i32* %addr) {
; CHECK-LABEL: Determining loop execution counts for: @changing_end_bound7
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
entry:
br label %loop
loop:
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%acc = phi i32 [ 0, %entry ], [ %acc.next, %loop ]
%val = load atomic i32, i32* %addr unordered, align 4
fence acquire
%acc.next = add i32 %acc, %val
%iv.next = add i32 %iv, -1
%n = load atomic i32, i32* %n_addr unordered, align 4
%cmp = icmp sgt i32 %iv.next, %n
br i1 %cmp, label %loop, label %loop.exit
loop.exit:
ret void
}
define void @max_overflow_se(i8 %n) mustprogress {
; CHECK-LABEL: Determining loop execution counts for: @max_overflow_se
; CHECK: Loop %loop: backedge-taken count is 0
; CHECK: Loop %loop: max backedge-taken count is 0
entry:
br label %loop
loop:
%i = phi i8 [ 63, %entry ], [ %i.next, %loop ]
%i.next = add nsw i8 %i, 63
%t = icmp slt i8 %i.next, %n
br i1 %t, label %loop, label %exit
exit:
ret void
}
; Show that we correctly realize that %i can overflow here as long as
; the early exit is taken before we branch on poison.
define void @max_overflow_me(i8 %n) mustprogress {
; CHECK-LABEL: Determining loop execution counts for: @max_overflow_me
; CHECK: Loop %loop: <multiple exits> Unpredictable backedge-taken count.
; CHECK: exit count for loop: 1
; CHECK: exit count for latch: ***COULDNOTCOMPUTE***
; CHECK: Loop %loop: max backedge-taken count is 1
entry:
br label %loop
loop:
%i = phi i8 [ 63, %entry ], [ %i.next, %latch ]
%j = phi i8 [ 0, %entry ], [ %j.next, %latch ]
%early.exit = icmp ne i8 %j, 1
br i1 %early.exit, label %latch, label %exit
latch:
%i.next = add nsw i8 %i, 63
%j.next = add nsw nuw i8 %j, 1
%t = icmp slt i8 %i.next, %n
br i1 %t, label %loop, label %exit
exit:
ret void
}
; Max backedge-taken count is zero.
define void @bool_stride(i1 %s, i1 %n) mustprogress {
; CHECK-LABEL: Determining loop execution counts for: @bool_stride
; CHECK: Loop %loop: Unpredictable backedge-taken count.
; CHECK: Loop %loop: Unpredictable max backedge-taken count.
entry:
br label %loop
loop:
%i = phi i1 [ -1, %entry ], [ %i.next, %loop ]
%i.next = add nsw i1 %i, %s
%t = icmp slt i1 %i.next, %n
br i1 %t, label %loop, label %exit
exit:
ret void
}
; This is a case where our max-backedge taken count logic happens to be
; able to prove a zero btc, but our symbolic logic doesn't due to a lack
; of context sensativity.
define void @ne_zero_max_btc(i32 %a) {
; CHECK-LABEL: Determining loop execution counts for: @ne_zero_max_btc
; CHECK: Loop %for.body: backedge-taken count is 0
; CHECK: Loop %for.body: max backedge-taken count is 0
entry:
%cmp = icmp slt i32 %a, 1
%spec.select = select i1 %cmp, i32 %a, i32 1
%cmp8 = icmp sgt i32 %a, 0
br i1 %cmp8, label %for.body.preheader, label %loopexit
for.body.preheader: ; preds = %if.then4.i.i
%umax = call i32 @llvm.umax.i32(i32 %spec.select, i32 1)
%umax.i.i = zext i32 %umax to i64
br label %for.body
for.body: ; preds = %for.inc, %for.body.preheader
%indvars.iv = phi i64 [ 0, %for.body.preheader ], [ %indvars.iv.next, %for.inc ]
call void @unknown()
br label %for.inc
for.inc: ; preds = %for.body
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond.i.not.i534 = icmp ne i64 %indvars.iv.next, %umax.i.i
br i1 %exitcond.i.not.i534, label %for.body, label %loopexit
loopexit:
ret void
}
declare void @unknown()
declare i32 @llvm.umax.i32(i32, i32)