[SCEV] Add more tests for MUL/UDIV folds.

Add additional test coverage for
llvm#157656 covering cases where
the dividend is not a multiple of the divisor, causing the revert of
70012fd.

(cherry picked from commit 6a726e9)

Author: fhahn

llvm/test/Analysis/ScalarEvolution/mul-udiv-folds.ll

@@ -123,3 +123,68 @@ loop:
 exit:
   ret void
 }
+
+declare void @use.i64(i64)
+
+define void @dividend_not_known_multiple_of_divisor(i64 %x) {
+; CHECK-LABEL: 'dividend_not_known_multiple_of_divisor'
+; CHECK-NEXT:  Classifying expressions for: @dividend_not_known_multiple_of_divisor
+; CHECK-NEXT:    %mul.2 = shl i64 %x, 1
+; CHECK-NEXT:    --> (2 * %x) U: [0,-1) S: [-9223372036854775808,9223372036854775807)
+; CHECK-NEXT:    %div.16 = lshr exact i64 %mul.2, 4
+; CHECK-NEXT:    --> ((2 * %x) /u 16) U: [0,1152921504606846976) S: [0,1152921504606846976)
+; CHECK-NEXT:    %m2 = and i64 %div.16, 1152921504606846974
+; CHECK-NEXT:    --> (2 * ((2 * %x) /u 32))<nuw><nsw> U: [0,1152921504606846975) S: [0,1152921504606846975)
+; CHECK-NEXT:    %m3 = mul i64 %div.16, 2
+; CHECK-NEXT:    --> (2 * ((2 * %x) /u 16))<nuw><nsw> U: [0,2305843009213693951) S: [0,2305843009213693951)
+; CHECK-NEXT:    %m4 = udiv i64 %m3, 4
+; CHECK-NEXT:    --> ((2 * ((2 * %x) /u 16))<nuw><nsw> /u 4) U: [0,576460752303423488) S: [0,576460752303423488)
+; CHECK-NEXT:  Determining loop execution counts for: @dividend_not_known_multiple_of_divisor
+;
+entry:
+  %mul.2 = shl i64 %x, 1
+  %div.16 = lshr exact i64 %mul.2, 4
+  %m2 = and i64 %div.16, 1152921504606846974
+  call void @use.i64(i64 %m2)
+
+  %m3 = mul i64 %div.16, 2
+  %m4 = udiv i64 %m3, 4
+  call void @use.i64(i64 %m4)
+  ret void
+}
+
+define void @btc_depends_on_div_mul(i64 %x) {
+; CHECK-LABEL: 'btc_depends_on_div_mul'
+; CHECK-NEXT:  Classifying expressions for: @btc_depends_on_div_mul
+; CHECK-NEXT:    %mul.2 = shl i64 %x, 1
+; CHECK-NEXT:    --> (2 * %x) U: [0,-1) S: [-9223372036854775808,9223372036854775807)
+; CHECK-NEXT:    %div.16 = lshr exact i64 %mul.2, 4
+; CHECK-NEXT:    --> ((2 * %x) /u 16) U: [0,1152921504606846976) S: [0,1152921504606846976)
+; CHECK-NEXT:    %masked = and i64 %div.16, 1152921504606846974
+; CHECK-NEXT:    --> (2 * ((2 * %x) /u 32))<nuw><nsw> U: [0,1152921504606846975) S: [0,1152921504606846975)
+; CHECK-NEXT:    %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT:    --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: (-2 + (2 * ((2 * %x) /u 32))<nuw><nsw>)<nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.next = add i64 %iv, 2
+; CHECK-NEXT:    --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: (2 * ((2 * %x) /u 32))<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:  Determining loop execution counts for: @btc_depends_on_div_mul
+; CHECK-NEXT:  Loop %loop: backedge-taken count is ((-2 + (2 * ((2 * %x) /u 32))<nuw><nsw>)<nsw> /u 2)
+; CHECK-NEXT:  Loop %loop: constant max backedge-taken count is i64 9223372036854775807
+; CHECK-NEXT:  Loop %loop: symbolic max backedge-taken count is ((-2 + (2 * ((2 * %x) /u 32))<nuw><nsw>)<nsw> /u 2)
+; CHECK-NEXT:  Loop %loop: Trip multiple is 1
+;
+entry:
+  %mul.2 = shl i64 %x, 1
+  %div.16 = lshr exact i64 %mul.2, 4
+  %masked = and i64 %div.16, 1152921504606846974
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+  call void @use.i64(i64 %iv)
+  %iv.next = add i64 %iv, 2
+  %ec = icmp eq i64 %iv.next, %masked
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret void
+}

llvm/test/Transforms/LoopStrengthReduce/duplicated-phis.ll

@@ -83,3 +83,41 @@ for.end:
   %res.0.lcssa = phi i64 [ 0, %entry ], [ %spec.select, %for.end.loopexit.unr-lcssa ]
   ret i64 %res.0.lcssa
 }
+
+define i64 @duplicated_phis_compare_uses_mul_udiv(i64 %x) {
+; CHECK-LABEL: define i64 @duplicated_phis_compare_uses_mul_udiv(
+; CHECK-SAME: i64 [[X:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    [[MUL_2:%.*]] = shl i64 [[X]], 1
+; CHECK-NEXT:    [[DIV_16:%.*]] = lshr i64 [[MUL_2]], 4
+; CHECK-NEXT:    [[MASKED:%.*]] = and i64 [[DIV_16]], 1152921504606846974
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV_1:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[IV_1_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    call void @clobber()
+; CHECK-NEXT:    [[IV_1_NEXT]] = add i64 [[IV_1]], 2
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[MASKED]], [[IV_1_NEXT]]
+; CHECK-NEXT:    br i1 [[EC]], label %[[EXIT:.*]], label %[[LOOP]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    ret i64 [[IV_1_NEXT]]
+;
+entry:
+  %mul.2 = shl i64 %x, 1
+  %div.16 = lshr exact i64 %mul.2, 4
+  %masked = and i64 %div.16, 1152921504606846974
+  br label %loop
+
+loop:
+  %iv.1 = phi i64 [ 0, %entry ], [ %iv.1.next, %loop ]
+  %iv.2 = phi i64 [ 0, %entry ], [ %iv.2.next, %loop ]
+  call void @clobber()
+  %iv.1.next = add i64 %iv.1, 2
+  %iv.2.next = add i64 %iv.2, 2
+  %ec = icmp eq i64 %iv.2.next, %masked
+  br i1 %ec, label %exit, label %loop
+
+exit:
+  ret i64 %iv.1.next
+}
+
+declare void @clobber()