[PATCH] D16402: Simplify (x >> y) <= x
David Majnemer via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 21 10:59:55 PST 2016
This revision was automatically updated to reflect the committed changes.
Closed by commit rL258422: [InstCombine] Simplify (x >> y) <= x (authored by majnemer).
Changed prior to commit:
http://reviews.llvm.org/D16402?vs=45520&id=45570#toc
Repository:
rL LLVM
http://reviews.llvm.org/D16402
Files:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/test/Transforms/InstSimplify/compare.ll
Index: llvm/trunk/test/Transforms/InstSimplify/compare.ll
===================================================================
--- llvm/trunk/test/Transforms/InstSimplify/compare.ll
+++ llvm/trunk/test/Transforms/InstSimplify/compare.ll
@@ -397,6 +397,22 @@
; CHECK: ret i1 true
}
+define i1 @lshr4(i32 %X, i32 %Y) {
+; CHECK-LABEL: @lshr4(
+ %A = lshr i32 %X, %Y
+ %C = icmp ule i32 %A, %X
+ ret i1 %C
+; CHECK: ret i1 true
+}
+
+define i1 @lshr5(i32 %X, i32 %Y) {
+; CHECK-LABEL: @lshr5(
+ %A = lshr i32 %X, %Y
+ %C = icmp ugt i32 %A, %X
+ ret i1 %C
+; CHECK: ret i1 false
+}
+
define i1 @ashr1(i32 %x) {
; CHECK-LABEL: @ashr1(
%s = ashr i32 -1, %x
Index: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp
@@ -2727,9 +2727,11 @@
}
}
+ // x >> y <=u x
// x udiv y <=u x.
- if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
- // icmp pred (X /u Y), X
+ if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) ||
+ match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) {
+ // icmp pred (X op Y), X
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
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