[llvm] 66b6698 - [NFC][InstCombine] Add some tests with sdiv-by-negative-power-of-two

[Roman Lebedev via llvm-commits]

Author: Roman Lebedev
Date: 2020-07-17T22:50:09+03:00
New Revision: 66b66988e613a2349d06600e12601ecbe8032256

URL: https://github.com/llvm/llvm-project/commit/66b66988e613a2349d06600e12601ecbe8032256
DIFF: https://github.com/llvm/llvm-project/commit/66b66988e613a2349d06600e12601ecbe8032256.diff

LOG: [NFC][InstCombine] Add some tests with sdiv-by-negative-power-of-two

Added: 
    llvm/test/Transforms/InstCombine/sdiv-of-non-negative-by-negative-power-of-two.ll

Modified: 
    

Removed: 
    


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diff  --git a/llvm/test/Transforms/InstCombine/sdiv-of-non-negative-by-negative-power-of-two.ll b/llvm/test/Transforms/InstCombine/sdiv-of-non-negative-by-negative-power-of-two.ll
new file mode 100644
index 000000000000..c10a98a41acb
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/sdiv-of-non-negative-by-negative-power-of-two.ll
@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; Fold
+;   x s/ (-1 << y)
+; to
+;   -(x >> y)
+; iff x is known non-negative.
+
+declare void @llvm.assume(i1)
+
+define i8 @t0(i8 %x, i8 %y) {
+; CHECK-LABEL: @t0(
+; CHECK-NEXT:    [[X_IS_NONNEGATIVE:%.*]] = icmp sgt i8 [[X:%.*]], -1
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_IS_NONNEGATIVE]])
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X]], -32
+; CHECK-NEXT:    ret i8 [[DIV]]
+;
+  %x_is_nonnegative = icmp sge i8 %x, 0
+  call void @llvm.assume(i1 %x_is_nonnegative)
+  %div = sdiv i8 %x, -32
+  ret i8 %div
+}
+define i8 @n1(i8 %x, i8 %y) {
+; CHECK-LABEL: @n1(
+; CHECK-NEXT:    [[X_IS_NONNEGATIVE:%.*]] = icmp sgt i8 [[X:%.*]], -2
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_IS_NONNEGATIVE]])
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X]], -32
+; CHECK-NEXT:    ret i8 [[DIV]]
+;
+  %x_is_nonnegative = icmp sge i8 %x, -1 ; could be negative
+  call void @llvm.assume(i1 %x_is_nonnegative)
+  %div = sdiv i8 %x, -32
+  ret i8 %div
+}
+define i8 @n2(i8 %x, i8 %y) {
+; CHECK-LABEL: @n2(
+; CHECK-NEXT:    [[X_IS_NONNEGATIVE:%.*]] = icmp sgt i8 [[X:%.*]], -1
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_IS_NONNEGATIVE]])
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X]], -31
+; CHECK-NEXT:    ret i8 [[DIV]]
+;
+  %x_is_nonnegative = icmp sge i8 %x, 0
+  call void @llvm.assume(i1 %x_is_nonnegative)
+  %div = sdiv i8 %x, -31 ; not a negative power of two
+  ret i8 %div
+}