From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Fri, 19 Jul 2019 11:29:18 +0000 (+0000)
Subject: [NFC][InstCombine] Tests for 'rem' formation from sub-of-mul-by-'div' (PR42673)
X-Git-Tag: llvmorg-11-init~13990
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9998585c47b97b31a5811ee0528029629937c063;p=platform%2Fupstream%2Fllvm.git

[NFC][InstCombine] Tests for 'rem' formation from sub-of-mul-by-'div' (PR42673)

https://rise4fun.com/Alive/8Rp
https://bugs.llvm.org/show_bug.cgi?id=42673

llvm-svn: 366565
---

diff --git a/llvm/test/Transforms/InstCombine/srem-via-sdiv-mul-sub.ll b/llvm/test/Transforms/InstCombine/srem-via-sdiv-mul-sub.ll
new file mode 100644
index 0000000..8690faa
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/srem-via-sdiv-mul-sub.ll
@@ -0,0 +1,117 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; Fold
+;   x - ((x / y) * y)
+; to
+;   x % y
+
+; Also,
+;   ((x / y) * y)
+; can then be simplified to
+;   x - (x % y)
+
+declare void @use8(i8)
+declare void @use2xi8(<2 x i8>)
+
+define i8 @t0_basic(i8 %x, i8 %y) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = sdiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+define <2 x i8> @t1_vector(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: @t1_vector(
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv <2 x i8> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use2xi8(<2 x i8> [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul <2 x i8> [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub <2 x i8> [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret <2 x i8> [[REM]]
+;
+  %div = sdiv <2 x i8> %x, %y
+  call void @use2xi8(<2 x i8> %div)
+  %roundXdownToMultipleOfY = mul <2 x i8> %div, %y
+  %rem = sub <2 x i8> %x, %roundXdownToMultipleOfY
+  ret <2 x i8> %rem
+}
+
+; Extra use
+
+define i8 @t4_extrause(i8 %x, i8 %y) {
+; CHECK-LABEL: @t4_extrause(
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    call void @use8(i8 [[ROUNDXDOWNTOMULTIPLEOFY]])
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = sdiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  call void @use8(i8 %roundXdownToMultipleOfY)
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+; Commutativity
+
+declare i8 @gen8()
+
+define i8 @t5_commutative(i8 %x) {
+; CHECK-LABEL: @t5_commutative(
+; CHECK-NEXT:    [[Y:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], [[Y]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[Y]], [[DIV]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %y = call i8 @gen8()
+  %div = sdiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %y, %div ; swapped
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+; Negative tests
+
+define i8 @n6_different_x(i8 %x0, i8 %x1, i8 %y) {
+; CHECK-LABEL: @n6_different_x(
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X0:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X1:%.*]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = sdiv i8 %x0, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  %rem = sub i8 %x1, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+define i8 @n6_different_y(i8 %x, i8 %y0, i8 %y1) {
+; CHECK-LABEL: @n6_different_y(
+; CHECK-NEXT:    [[DIV:%.*]] = sdiv i8 [[X:%.*]], [[Y0:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y1:%.*]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = sdiv i8 %x, %y0
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y1
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
diff --git a/llvm/test/Transforms/InstCombine/urem-via-udiv-mul-sub.ll b/llvm/test/Transforms/InstCombine/urem-via-udiv-mul-sub.ll
new file mode 100644
index 0000000..0e28a0d
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/urem-via-udiv-mul-sub.ll
@@ -0,0 +1,117 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt %s -instcombine -S | FileCheck %s
+
+; Fold
+;   x - ((x / y) * y)
+; to
+;   x % y
+
+; Also,
+;   ((x / y) * y)
+; can then be simplified to
+;   x - (x % y)
+
+declare void @use8(i8)
+declare void @use2xi8(<2 x i8>)
+
+define i8 @t0_basic(i8 %x, i8 %y) {
+; CHECK-LABEL: @t0_basic(
+; CHECK-NEXT:    [[DIV:%.*]] = udiv i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = udiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+define <2 x i8> @t1_vector(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: @t1_vector(
+; CHECK-NEXT:    [[DIV:%.*]] = udiv <2 x i8> [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use2xi8(<2 x i8> [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul <2 x i8> [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub <2 x i8> [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret <2 x i8> [[REM]]
+;
+  %div = udiv <2 x i8> %x, %y
+  call void @use2xi8(<2 x i8> %div)
+  %roundXdownToMultipleOfY = mul <2 x i8> %div, %y
+  %rem = sub <2 x i8> %x, %roundXdownToMultipleOfY
+  ret <2 x i8> %rem
+}
+
+; Extra use
+
+define i8 @t4_extrause(i8 %x, i8 %y) {
+; CHECK-LABEL: @t4_extrause(
+; CHECK-NEXT:    [[DIV:%.*]] = udiv i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    call void @use8(i8 [[ROUNDXDOWNTOMULTIPLEOFY]])
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = udiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  call void @use8(i8 %roundXdownToMultipleOfY)
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+; Commutativity
+
+declare i8 @gen8()
+
+define i8 @t5_commutative(i8 %x) {
+; CHECK-LABEL: @t5_commutative(
+; CHECK-NEXT:    [[Y:%.*]] = call i8 @gen8()
+; CHECK-NEXT:    [[DIV:%.*]] = udiv i8 [[X:%.*]], [[Y]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[Y]], [[DIV]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %y = call i8 @gen8()
+  %div = udiv i8 %x, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %y, %div ; swapped
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+; Negative tests
+
+define i8 @n6_different_x(i8 %x0, i8 %x1, i8 %y) {
+; CHECK-LABEL: @n6_different_x(
+; CHECK-NEXT:    [[DIV:%.*]] = udiv i8 [[X0:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X1:%.*]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = udiv i8 %x0, %y
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y
+  %rem = sub i8 %x1, %roundXdownToMultipleOfY
+  ret i8 %rem
+}
+
+define i8 @n6_different_y(i8 %x, i8 %y0, i8 %y1) {
+; CHECK-LABEL: @n6_different_y(
+; CHECK-NEXT:    [[DIV:%.*]] = udiv i8 [[X:%.*]], [[Y0:%.*]]
+; CHECK-NEXT:    call void @use8(i8 [[DIV]])
+; CHECK-NEXT:    [[ROUNDXDOWNTOMULTIPLEOFY:%.*]] = mul i8 [[DIV]], [[Y1:%.*]]
+; CHECK-NEXT:    [[REM:%.*]] = sub i8 [[X]], [[ROUNDXDOWNTOMULTIPLEOFY]]
+; CHECK-NEXT:    ret i8 [[REM]]
+;
+  %div = udiv i8 %x, %y0
+  call void @use8(i8 %div)
+  %roundXdownToMultipleOfY = mul i8 %div, %y1
+  %rem = sub i8 %x, %roundXdownToMultipleOfY
+  ret i8 %rem
+}