Fold icmp ugt (udiv X, Y), X to false. Spotted by my super-optimizer
in 186.crafty.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143209 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 31cbbba..6bef0ae 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1574,6 +1574,9 @@
// 'srem x, CI2' produces (-|CI2|, |CI2|).
Upper = CI2->getValue().abs();
Lower = (-Upper) + 1;
+ } else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
+ // 'udiv CI2, x' produces [0, CI2].
+ Upper = CI2->getValue();
} else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
// 'udiv x, CI2' produces [0, UINT_MAX / CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
@@ -1880,6 +1883,15 @@
}
}
+ // x udiv y <=u x.
+ if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
+ // icmp pred (X /u Y), X
+ if (Pred == ICmpInst::ICMP_UGT)
+ return getFalse(ITy);
+ if (Pred == ICmpInst::ICMP_ULE)
+ return getTrue(ITy);
+ }
+
if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
LBO->getOperand(1) == RBO->getOperand(1)) {
switch (LBO->getOpcode()) {
diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll
index 3ece118..57727c9 100644
--- a/test/Transforms/InstSimplify/compare.ll
+++ b/test/Transforms/InstSimplify/compare.ll
@@ -300,6 +300,30 @@
; CHECK: ret i1 true
}
+define i1 @udiv3(i32 %X, i32 %Y) {
+; CHECK: @udiv3
+ %A = udiv i32 %X, %Y
+ %C = icmp ugt i32 %A, %X
+ ret i1 %C
+; CHECK: ret i1 false
+}
+
+define i1 @udiv4(i32 %X, i32 %Y) {
+; CHECK: @udiv4
+ %A = udiv i32 %X, %Y
+ %C = icmp ule i32 %A, %X
+ ret i1 %C
+; CHECK: ret i1 true
+}
+
+define i1 @udiv5(i32 %X) {
+; CHECK: @udiv5
+ %A = udiv i32 123, %X
+ %C = icmp ugt i32 %A, 124
+ ret i1 %C
+; CHECK: ret i1 false
+}
+
define i1 @sdiv1(i32 %X) {
; CHECK: @sdiv1
%A = sdiv i32 %X, 1000000