forked from OSchip/llvm-project
110 lines
3.9 KiB
LLVM
110 lines
3.9 KiB
LLVM
; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
|
|
|
|
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
|
|
|
|
@A = weak global [1000 x i32] zeroinitializer, align 32
|
|
|
|
; The resulting predicate is i16 {0,+,1} <nssw>, meanining
|
|
; that the resulting backedge expression will be valid for:
|
|
; (1 + (-1 smax %M)) <= MAX_INT16
|
|
;
|
|
; At the limit condition for M (MAX_INT16 - 1) we have in the
|
|
; last iteration:
|
|
; i0 <- MAX_INT16
|
|
; i0.ext <- MAX_INT16
|
|
;
|
|
; and therefore no wrapping happend for i0 or i0.ext
|
|
; throughout the execution of the loop. The resulting predicated
|
|
; backedge taken count is correct.
|
|
|
|
; CHECK: Classifying expressions for: @test1
|
|
; CHECK: %i.0.ext = sext i16 %i.0 to i32
|
|
; CHECK-NEXT: --> (sext i16 {0,+,1}<%bb3> to i32)
|
|
; CHECK: Loop %bb3: Unpredictable backedge-taken count.
|
|
; CHECK-NEXT: Loop %bb3: Unpredictable max backedge-taken count.
|
|
; CHECK-NEXT: Loop %bb3: Predicated backedge-taken count is (1 + (-1 smax %M))
|
|
; CHECK-NEXT: Predicates:
|
|
; CHECK-NEXT: {0,+,1}<%bb3> Added Flags: <nssw>
|
|
define void @test1(i32 %N, i32 %M) {
|
|
entry:
|
|
br label %bb3
|
|
|
|
bb: ; preds = %bb3
|
|
%tmp = getelementptr [1000 x i32], [1000 x i32]* @A, i32 0, i16 %i.0 ; <i32*> [#uses=1]
|
|
store i32 123, i32* %tmp
|
|
%tmp2 = add i16 %i.0, 1 ; <i32> [#uses=1]
|
|
br label %bb3
|
|
|
|
bb3: ; preds = %bb, %entry
|
|
%i.0 = phi i16 [ 0, %entry ], [ %tmp2, %bb ] ; <i32> [#uses=3]
|
|
%i.0.ext = sext i16 %i.0 to i32
|
|
%tmp3 = icmp sle i32 %i.0.ext, %M ; <i1> [#uses=1]
|
|
br i1 %tmp3, label %bb, label %bb5
|
|
|
|
bb5: ; preds = %bb3
|
|
br label %return
|
|
|
|
return: ; preds = %bb5
|
|
ret void
|
|
}
|
|
|
|
; The predicated backedge taken count is:
|
|
; (2 + (zext i16 %Start to i32) + ((-2 + (-1 * (sext i16 %Start to i32)))
|
|
; smax (-1 + (-1 * %M)))
|
|
; )
|
|
|
|
; -1 + (-1 * %M) <= (-2 + (-1 * (sext i16 %Start to i32))
|
|
; The predicated backedge taken count is 0.
|
|
; From the IR, this is correct since we will bail out at the
|
|
; first iteration.
|
|
|
|
|
|
; * -1 + (-1 * %M) > (-2 + (-1 * (sext i16 %Start to i32))
|
|
; or: %M < 1 + (sext i16 %Start to i32)
|
|
;
|
|
; The predicated backedge taken count is 1 + (zext i16 %Start to i32) - %M
|
|
;
|
|
; If %M >= MIN_INT + 1, this predicated backedge taken count would be correct (even
|
|
; without predicates). However, for %M < MIN_INT this would be an infinite loop.
|
|
; In these cases, the {%Start,+,-1} <nusw> predicate would be false, as the
|
|
; final value of the expression {%Start,+,-1} expression (%M - 1) would not be
|
|
; representable as an i16.
|
|
|
|
; There is also a limit case here where the value of %M is MIN_INT. In this case
|
|
; we still have an infinite loop, since icmp sge %x, MIN_INT will always return
|
|
; true.
|
|
|
|
; CHECK: Classifying expressions for: @test2
|
|
|
|
; CHECK: %i.0.ext = sext i16 %i.0 to i32
|
|
; CHECK-NEXT: --> (sext i16 {%Start,+,-1}<%bb3> to i32)
|
|
; CHECK: Loop %bb3: Unpredictable backedge-taken count.
|
|
; CHECK-NEXT: Loop %bb3: Unpredictable max backedge-taken count.
|
|
; CHECK-NEXT: Loop %bb3: Predicated backedge-taken count is (1 + (sext i16 %Start to i32) + (-1 * ((1 + (sext i16 %Start to i32))<nsw> smin %M)))
|
|
; CHECK-NEXT: Predicates:
|
|
; CHECK-NEXT: {%Start,+,-1}<%bb3> Added Flags: <nssw>
|
|
|
|
define void @test2(i32 %N, i32 %M, i16 %Start) {
|
|
entry:
|
|
br label %bb3
|
|
|
|
bb: ; preds = %bb3
|
|
%tmp = getelementptr [1000 x i32], [1000 x i32]* @A, i32 0, i16 %i.0 ; <i32*> [#uses=1]
|
|
store i32 123, i32* %tmp
|
|
%tmp2 = sub i16 %i.0, 1 ; <i32> [#uses=1]
|
|
br label %bb3
|
|
|
|
bb3: ; preds = %bb, %entry
|
|
%i.0 = phi i16 [ %Start, %entry ], [ %tmp2, %bb ] ; <i32> [#uses=3]
|
|
%i.0.ext = sext i16 %i.0 to i32
|
|
%tmp3 = icmp sge i32 %i.0.ext, %M ; <i1> [#uses=1]
|
|
br i1 %tmp3, label %bb, label %bb5
|
|
|
|
bb5: ; preds = %bb3
|
|
br label %return
|
|
|
|
return: ; preds = %bb5
|
|
ret void
|
|
}
|
|
|