1 files changed, 93 insertions, 0 deletions
diff --git a/llvm/test/Analysis/ScalarEvolution/extract-lowbits-variablemask.ll b/llvm/test/Analysis/ScalarEvolution/extract-lowbits-variablemask.ll
new file mode 100644
index 00000000000..cd73cf366b8
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/extract-lowbits-variablemask.ll
@@ -0,0 +1,93 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt -S -analyze -scalar-evolution < %s | FileCheck %s
+
+; These testcases aren't *identical* but they have the same/similar meaning.
+
+; The obvious case.
+define i32 @mul(i32 %val, i32 %num) nounwind {
+; CHECK-LABEL: 'mul'
+; CHECK-NEXT:  Classifying expressions for: @mul
+; CHECK-NEXT:    %tmp1 = mul i32 %val, %num
+; CHECK-NEXT:    -->  (%val * %num) U: full-set S: full-set
+; CHECK-NEXT:    %tmp2 = udiv i32 %tmp1, %num
+; CHECK-NEXT:    -->  ((%val * %num) /u %num) U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @mul
+;
+  %tmp1 = mul i32 %val, %num
+  %tmp2 = udiv i32 %tmp1, %num
+  ret i32 %tmp2
+}
+
+; Or, it could be any number of equivalent patterns with mask:
+;   a) x &  (1 << nbits) - 1
+;   b) x & ~(-1 << nbits)
+;   c) x &  (-1 >> (32 - y))
+;   d) x << (32 - y) >> (32 - y)
+
+define i32 @mask_a(i32 %val, i32 %numlowbits) nounwind {
+; CHECK-LABEL: 'mask_a'
+; CHECK-NEXT:  Classifying expressions for: @mask_a
+; CHECK-NEXT:    %onebit = shl i32 1, %numlowbits
+; CHECK-NEXT:    -->  %onebit U: full-set S: full-set
+; CHECK-NEXT:    %mask = add nsw i32 %onebit, -1
+; CHECK-NEXT:    -->  (-1 + %onebit) U: full-set S: full-set
+; CHECK-NEXT:    %masked = and i32 %mask, %val
+; CHECK-NEXT:    -->  %masked U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @mask_a
+;
+  %onebit = shl i32 1, %numlowbits
+  %mask = add nsw i32 %onebit, -1
+  %masked = and i32 %mask, %val
+  ret i32 %masked
+}
+
+define i32 @mask_b(i32 %val, i32 %numlowbits) nounwind {
+; CHECK-LABEL: 'mask_b'
+; CHECK-NEXT:  Classifying expressions for: @mask_b
+; CHECK-NEXT:    %notmask = shl i32 -1, %numlowbits
+; CHECK-NEXT:    -->  %notmask U: full-set S: full-set
+; CHECK-NEXT:    %mask = xor i32 %notmask, -1
+; CHECK-NEXT:    -->  (-1 + (-1 * %notmask)) U: full-set S: full-set
+; CHECK-NEXT:    %masked = and i32 %mask, %val
+; CHECK-NEXT:    -->  %masked U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @mask_b
+;
+  %notmask = shl i32 -1, %numlowbits
+  %mask = xor i32 %notmask, -1
+  %masked = and i32 %mask, %val
+  ret i32 %masked
+}
+
+define i32 @mask_c(i32 %val, i32 %numlowbits) nounwind {
+; CHECK-LABEL: 'mask_c'
+; CHECK-NEXT:  Classifying expressions for: @mask_c
+; CHECK-NEXT:    %numhighbits = sub i32 32, %numlowbits
+; CHECK-NEXT:    -->  (32 + (-1 * %numlowbits)) U: full-set S: full-set
+; CHECK-NEXT:    %mask = lshr i32 -1, %numhighbits
+; CHECK-NEXT:    -->  %mask U: full-set S: full-set
+; CHECK-NEXT:    %masked = and i32 %mask, %val
+; CHECK-NEXT:    -->  %masked U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @mask_c
+;
+  %numhighbits = sub i32 32, %numlowbits
+  %mask = lshr i32 -1, %numhighbits
+  %masked = and i32 %mask, %val
+  ret i32 %masked
+}
+
+define i32 @mask_d(i32 %val, i32 %numlowbits) nounwind {
+; CHECK-LABEL: 'mask_d'
+; CHECK-NEXT:  Classifying expressions for: @mask_d
+; CHECK-NEXT:    %numhighbits = sub i32 32, %numlowbits
+; CHECK-NEXT:    -->  (32 + (-1 * %numlowbits)) U: full-set S: full-set
+; CHECK-NEXT:    %highbitscleared = shl i32 %val, %numhighbits
+; CHECK-NEXT:    -->  %highbitscleared U: full-set S: full-set
+; CHECK-NEXT:    %masked = lshr i32 %highbitscleared, %numhighbits
+; CHECK-NEXT:    -->  %masked U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @mask_d
+;
+  %numhighbits = sub i32 32, %numlowbits
+  %highbitscleared = shl i32 %val, %numhighbits
+  %masked = lshr i32 %highbitscleared, %numhighbits
+  ret i32 %masked
+}