<div dir="ltr">Sorry for the necro-post, but did this get verified with an SMT solver?<div><br></div><div>Sanjay (CC'd) even provided links to example code for using an SMT solver to verify it in <a href="http://llvm.org/bugs/show_bug.cgi?id=19958#c9">http://llvm.org/bugs/show_bug.cgi?id=19958#c9</a><br><div><br></div><div>-- Sean Silva</div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jul 22, 2014 at 12:19 PM, Suyog Sarda <span dir="ltr"><<a href="mailto:suyog.sarda@samsung.com" target="_blank">suyog.sarda@samsung.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: suyog<br>
Date: Tue Jul 22 14:19:36 2014<br>
New Revision: 213678<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=213678&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=213678&view=rev</a><br>
Log:<br>
This patch implements optimization as mentioned in PR19753: Optimize comparisons with "ashr/lshr exact" of a constanst.<br>
It handles the errors which were seen in PR19958 where wrong code was being emitted due to earlier patch.<br>
Added code for lshr as well as non-exact right shifts.<br>
<br>
It implements :<br>
(icmp eq/ne (ashr/lshr const2, A), const1)" -><br>
(icmp eq/ne A, Log2(const2/const1)) -><br>
(icmp eq/ne A, Log2(const2) - Log2(const1))<br>
<br>
Differential Revision: <a href="http://reviews.llvm.org/D4068" target="_blank">http://reviews.llvm.org/D4068</a><br>
<br>
<br>
Added:<br>
llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll<br>
Modified:<br>
llvm/trunk/lib/Transforms/InstCombine/InstCombine.h<br>
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp<br>
<br>
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombine.h<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombine.h?rev=213678&r1=213677&r2=213678&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombine.h?rev=213678&r1=213677&r2=213678&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Transforms/InstCombine/InstCombine.h (original)<br>
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombine.h Tue Jul 22 14:19:36 2014<br>
@@ -172,6 +172,8 @@ public:<br>
ConstantInt *DivRHS);<br>
Instruction *FoldICmpShrCst(ICmpInst &ICI, BinaryOperator *DivI,<br>
ConstantInt *DivRHS);<br>
+ Instruction *FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,<br>
+ ConstantInt *CI1, ConstantInt *CI2);<br>
Instruction *FoldICmpAddOpCst(Instruction &ICI, Value *X, ConstantInt *CI,<br>
ICmpInst::Predicate Pred);<br>
Instruction *FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS,<br>
<br>
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=213678&r1=213677&r2=213678&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=213678&r1=213677&r2=213678&view=diff</a><br>
==============================================================================<br>
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)<br>
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Tue Jul 22 14:19:36 2014<br>
@@ -1044,6 +1044,90 @@ Instruction *InstCombiner::FoldICmpShrCs<br>
return nullptr;<br>
}<br>
<br>
+/// FoldICmpCstShrCst - Handle "(icmp eq/ne (ashr/lshr const2, A), const1)" -><br>
+/// (icmp eq/ne A, Log2(const2/const1)) -><br>
+/// (icmp eq/ne A, Log2(const2) - Log2(const1)).<br>
+Instruction *InstCombiner::FoldICmpCstShrCst(ICmpInst &I, Value *Op, Value *A,<br>
+ ConstantInt *CI1,<br>
+ ConstantInt *CI2) {<br>
+ assert(I.isEquality() && "Cannot fold icmp gt/lt");<br>
+<br>
+ auto getConstant = [&I, this](bool IsTrue) {<br>
+ if (I.getPredicate() == I.ICMP_NE)<br>
+ IsTrue = !IsTrue;<br>
+ return ReplaceInstUsesWith(I, ConstantInt::get(I.getType(), IsTrue));<br>
+ };<br>
+<br>
+ auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) {<br>
+ if (I.getPredicate() == I.ICMP_NE)<br>
+ Pred = CmpInst::getInversePredicate(Pred);<br>
+ return new ICmpInst(Pred, LHS, RHS);<br>
+ };<br>
+<br>
+ APInt AP1 = CI1->getValue();<br>
+ APInt AP2 = CI2->getValue();<br>
+<br>
+ if (!AP1) {<br>
+ if (!AP2) {<br>
+ // Both Constants are 0.<br>
+ return getConstant(true);<br>
+ }<br>
+<br>
+ if (cast<BinaryOperator>(Op)->isExact())<br>
+ return getConstant(false);<br>
+<br>
+ if (AP2.isNegative()) {<br>
+ // MSB is set, so a lshr with a large enough 'A' would be undefined.<br>
+ return getConstant(false);<br>
+ }<br>
+<br>
+ // 'A' must be large enough to shift out the highest set bit.<br>
+ return getICmp(I.ICMP_UGT, A,<br>
+ ConstantInt::get(A->getType(), AP2.logBase2()));<br>
+ }<br>
+<br>
+ if (!AP2) {<br>
+ // Shifting 0 by any value gives 0.<br>
+ return getConstant(false);<br>
+ }<br>
+<br>
+ bool IsAShr = isa<AShrOperator>(Op);<br>
+ if (AP1 == AP2) {<br>
+ if (AP1.isAllOnesValue() && IsAShr) {<br>
+ // Arithmatic shift of -1 is always -1.<br>
+ return getConstant(true);<br>
+ }<br>
+ return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType()));<br>
+ }<br>
+<br>
+ if (IsAShr) {<br>
+ if (AP1.isNegative() != AP2.isNegative()) {<br>
+ // Arithmetic shift will never change the sign.<br>
+ return getConstant(false);<br>
+ }<br>
+ // Both the constants are negative, take their positive to calculate<br>
+ // log.<br>
+ if (AP1.isNegative()) {<br>
+ AP1 = -AP1;<br>
+ AP2 = -AP2;<br>
+ }<br>
+ }<br>
+<br>
+ if (AP1.ugt(AP2)) {<br>
+ // Right-shifting will not increase the value.<br>
+ return getConstant(false);<br>
+ }<br>
+<br>
+ // Get the distance between the highest bit that's set.<br>
+ int Shift = AP2.logBase2() - AP1.logBase2();<br>
+<br>
+ // Use lshr here, since we've canonicalized to +ve numbers.<br>
+ if (AP1 == AP2.lshr(Shift))<br>
+ return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift));<br>
+<br>
+ // Shifting const2 will never be equal to const1.<br>
+ return getConstant(false);<br>
+}<br>
<br>
/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)".<br>
///<br>
@@ -2469,6 +2553,15 @@ Instruction *InstCombiner::visitICmpInst<br>
Builder->getInt(CI->getValue()-1));<br>
}<br>
<br>
+ // (icmp eq/ne (ashr/lshr const2, A), const1)<br>
+ if (I.isEquality()) {<br>
+ ConstantInt *CI2;<br>
+ if (match(Op0, m_AShr(m_ConstantInt(CI2), m_Value(A))) ||<br>
+ match(Op0, m_LShr(m_ConstantInt(CI2), m_Value(A)))) {<br>
+ return FoldICmpCstShrCst(I, Op0, A, CI, CI2);<br>
+ }<br>
+ }<br>
+<br>
// If this comparison is a normal comparison, it demands all<br>
// bits, if it is a sign bit comparison, it only demands the sign bit.<br>
bool UnusedBit;<br>
<br>
Added: llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll?rev=213678&view=auto" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll?rev=213678&view=auto</a><br>
==============================================================================<br>
--- llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll (added)<br>
+++ llvm/trunk/test/Transforms/InstCombine/icmp-shr.ll Tue Jul 22 14:19:36 2014<br>
@@ -0,0 +1,677 @@<br>
+; RUN: opt < %s -instcombine -S | FileCheck %s<br>
+<br>
+target datalayout = "e-p:64:64:64-p1:16:16:16-p2:32:32:32-p3:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_both_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_lshr_eq_both_zero(i8 %a) {<br>
+ %shr = lshr exact i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_both_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_eq_both_zero(i8 %a) {<br>
+ %shr = ashr exact i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_both_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_lshr_eq_both_zero(i8 %a) {<br>
+ %shr = lshr i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_both_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_ashr_eq_both_zero(i8 %a) {<br>
+ %shr = ashr i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_both_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_lshr_ne_both_zero(i8 %a) {<br>
+ %shr = lshr exact i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_both_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_ne_both_zero(i8 %a) {<br>
+ %shr = ashr exact i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_both_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_lshr_ne_both_zero(i8 %a) {<br>
+ %shr = lshr i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_both_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_ashr_ne_both_zero(i8 %a) {<br>
+ %shr = ashr i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_last_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_lshr_eq_last_zero(i8 %a) {<br>
+ %shr = lshr exact i8 128, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_last_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_eq_last_zero(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_last_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_lshr_ne_last_zero(i8 %a) {<br>
+ %shr = lshr exact i8 128, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_last_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_ne_last_zero(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_last_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_lshr_eq_last_zero(i8 %a) {<br>
+ %shr = lshr i8 128, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_last_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_ashr_eq_last_zero(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_last_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_lshr_ne_last_zero(i8 %a) {<br>
+ %shr = lshr i8 128, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_last_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_ashr_ne_last_zero(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_eq_msb_low_last_zero<br>
+; CHECK-NEXT: icmp ugt i8 %a, 6<br>
+define i1 @lshr_eq_msb_low_last_zero(i8 %a) {<br>
+ %shr = lshr i8 127, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_eq_msb_low_second_zero<br>
+; CHECK-NEXT: icmp ugt i8 %a, 6<br>
+define i1 @ashr_eq_msb_low_second_zero(i8 %a) {<br>
+ %shr = ashr i8 127, %a<br>
+ %cmp = icmp eq i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_ne_msb_low_last_zero<br>
+; CHECK-NEXT: icmp ult i8 %a, 7<br>
+define i1 @lshr_ne_msb_low_last_zero(i8 %a) {<br>
+ %shr = lshr i8 127, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_ne_msb_low_second_zero<br>
+; CHECK-NEXT: icmp ult i8 %a, 7<br>
+define i1 @ashr_ne_msb_low_second_zero(i8 %a) {<br>
+ %shr = ashr i8 127, %a<br>
+ %cmp = icmp ne i8 %shr, 0<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_eq_first_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @lshr_eq_first_zero(i8 %a) {<br>
+ %shr = lshr i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 2<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_eq_first_zero<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @ashr_eq_first_zero(i8 %a) {<br>
+ %shr = ashr i8 0, %a<br>
+ %cmp = icmp eq i8 %shr, 2<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_ne_first_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @lshr_ne_first_zero(i8 %a) {<br>
+ %shr = lshr i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 2<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_ne_first_zero<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @ashr_ne_first_zero(i8 %a) {<br>
+ %shr = ashr i8 0, %a<br>
+ %cmp = icmp ne i8 %shr, 2<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_eq_both_minus1<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @ashr_eq_both_minus1(i8 %a) {<br>
+ %shr = ashr i8 -1, %a<br>
+ %cmp = icmp eq i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_ne_both_minus1<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @ashr_ne_both_minus1(i8 %a) {<br>
+ %shr = ashr i8 -1, %a<br>
+ %cmp = icmp ne i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_both_minus1<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_eq_both_minus1(i8 %a) {<br>
+ %shr = ashr exact i8 -1, %a<br>
+ %cmp = icmp eq i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_both_minus1<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_ne_both_minus1(i8 %a) {<br>
+ %shr = ashr exact i8 -1, %a<br>
+ %cmp = icmp ne i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_eq_both_equal<br>
+; CHECK-NEXT: icmp eq i8 %a, 0<br>
+define i1 @ashr_eq_both_equal(i8 %a) {<br>
+ %shr = ashr i8 128, %a<br>
+ %cmp = icmp eq i8 %shr, 128<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_ne_both_equal<br>
+; CHECK-NEXT: icmp ne i8 %a, 0<br>
+define i1 @ashr_ne_both_equal(i8 %a) {<br>
+ %shr = ashr i8 128, %a<br>
+ %cmp = icmp ne i8 %shr, 128<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_eq_both_equal<br>
+; CHECK-NEXT: icmp eq i8 %a, 0<br>
+define i1 @lshr_eq_both_equal(i8 %a) {<br>
+ %shr = lshr i8 127, %a<br>
+ %cmp = icmp eq i8 %shr, 127<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_ne_both_equal<br>
+; CHECK-NEXT: icmp ne i8 %a, 0<br>
+define i1 @lshr_ne_both_equal(i8 %a) {<br>
+ %shr = lshr i8 127, %a<br>
+ %cmp = icmp ne i8 %shr, 127<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_both_equal<br>
+; CHECK-NEXT: icmp eq i8 %a, 0<br>
+define i1 @exact_ashr_eq_both_equal(i8 %a) {<br>
+ %shr = ashr exact i8 128, %a<br>
+ %cmp = icmp eq i8 %shr, 128<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_both_equal<br>
+; CHECK-NEXT: icmp ne i8 %a, 0<br>
+define i1 @exact_ashr_ne_both_equal(i8 %a) {<br>
+ %shr = ashr exact i8 128, %a<br>
+ %cmp = icmp ne i8 %shr, 128<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_both_equal<br>
+; CHECK-NEXT: icmp eq i8 %a, 0<br>
+define i1 @exact_lshr_eq_both_equal(i8 %a) {<br>
+ %shr = lshr exact i8 126, %a<br>
+ %cmp = icmp eq i8 %shr, 126<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_both_equal<br>
+; CHECK-NEXT: icmp ne i8 %a, 0<br>
+define i1 @exact_lshr_ne_both_equal(i8 %a) {<br>
+ %shr = lshr exact i8 126, %a<br>
+ %cmp = icmp ne i8 %shr, 126<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_opposite_msb<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_eq_opposite_msb(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_eq_opposite_msb<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @ashr_eq_opposite_msb(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_opposite_msb<br>
+; CHECK-NEXT: icmp eq i8 %a, 7<br>
+define i1 @exact_lshr_eq_opposite_msb(i8 %a) {<br>
+ %shr = lshr exact i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_eq_opposite_msb<br>
+; CHECK-NEXT: icmp eq i8 %a, 7<br>
+define i1 @lshr_eq_opposite_msb(i8 %a) {<br>
+ %shr = lshr i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_opposite_msb<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_ne_opposite_msb(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @ashr_ne_opposite_msb<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @ashr_ne_opposite_msb(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_opposite_msb<br>
+; CHECK-NEXT: icmp ne i8 %a, 7<br>
+define i1 @exact_lshr_ne_opposite_msb(i8 %a) {<br>
+ %shr = lshr exact i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @lshr_ne_opposite_msb<br>
+; CHECK-NEXT: icmp ne i8 %a, 7<br>
+define i1 @lshr_ne_opposite_msb(i8 %a) {<br>
+ %shr = lshr i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_shift_gt<br>
+; CHECK-NEXT : ret i1 false<br>
+define i1 @exact_ashr_eq_shift_gt(i8 %a) {<br>
+ %shr = ashr exact i8 -2, %a<br>
+ %cmp = icmp eq i8 %shr, -8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_shift_gt<br>
+; CHECK-NEXT : ret i1 true<br>
+define i1 @exact_ashr_ne_shift_gt(i8 %a) {<br>
+ %shr = ashr exact i8 -2, %a<br>
+ %cmp = icmp ne i8 %shr, -8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_shift_gt<br>
+; CHECK-NEXT : ret i1 false<br>
+define i1 @nonexact_ashr_eq_shift_gt(i8 %a) {<br>
+ %shr = ashr i8 -2, %a<br>
+ %cmp = icmp eq i8 %shr, -8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_shift_gt<br>
+; CHECK-NEXT : ret i1 true<br>
+define i1 @nonexact_ashr_ne_shift_gt(i8 %a) {<br>
+ %shr = ashr i8 -2, %a<br>
+ %cmp = icmp ne i8 %shr, -8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_shift_gt<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_lshr_eq_shift_gt(i8 %a) {<br>
+ %shr = lshr exact i8 2, %a<br>
+ %cmp = icmp eq i8 %shr, 8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_shift_gt<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_lshr_ne_shift_gt(i8 %a) {<br>
+ %shr = lshr exact i8 2, %a<br>
+ %cmp = icmp ne i8 %shr, 8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_shift_gt<br>
+; CHECK-NEXT : ret i1 false<br>
+define i1 @nonexact_lshr_eq_shift_gt(i8 %a) {<br>
+ %shr = lshr i8 2, %a<br>
+ %cmp = icmp eq i8 %shr, 8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_shift_gt<br>
+; CHECK-NEXT : ret i1 true<br>
+define i1 @nonexact_lshr_ne_shift_gt(i8 %a) {<br>
+ %shr = ashr i8 2, %a<br>
+ %cmp = icmp ne i8 %shr, 8<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq<br>
+; CHECK-NEXT: icmp eq i8 %a, 7<br>
+define i1 @exact_ashr_eq(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne<br>
+; CHECK-NEXT: icmp ne i8 %a, 7<br>
+define i1 @exact_ashr_ne(i8 %a) {<br>
+ %shr = ashr exact i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq<br>
+; CHECK-NEXT: icmp eq i8 %a, 2<br>
+define i1 @exact_lshr_eq(i8 %a) {<br>
+ %shr = lshr exact i8 4, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne<br>
+; CHECK-NEXT: icmp ne i8 %a, 2<br>
+define i1 @exact_lshr_ne(i8 %a) {<br>
+ %shr = lshr exact i8 4, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq<br>
+; CHECK-NEXT: icmp eq i8 %a, 7<br>
+define i1 @nonexact_ashr_eq(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp eq i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne<br>
+; CHECK-NEXT: icmp ne i8 %a, 7<br>
+define i1 @nonexact_ashr_ne(i8 %a) {<br>
+ %shr = ashr i8 -128, %a<br>
+ %cmp = icmp ne i8 %shr, -1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq<br>
+; CHECK-NEXT: icmp eq i8 %a, 2<br>
+define i1 @nonexact_lshr_eq(i8 %a) {<br>
+ %shr = lshr i8 4, %a<br>
+ %cmp = icmp eq i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne<br>
+; CHECK-NEXT: icmp ne i8 %a, 2<br>
+define i1 @nonexact_lshr_ne(i8 %a) {<br>
+ %shr = lshr i8 4, %a<br>
+ %cmp = icmp ne i8 %shr, 1<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_exactdiv<br>
+; CHECK-NEXT: icmp eq i8 %a, 4<br>
+define i1 @exact_lshr_eq_exactdiv(i8 %a) {<br>
+ %shr = lshr exact i8 80, %a<br>
+ %cmp = icmp eq i8 %shr, 5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_exactdiv<br>
+; CHECK-NEXT: icmp ne i8 %a, 4<br>
+define i1 @exact_lshr_ne_exactdiv(i8 %a) {<br>
+ %shr = lshr exact i8 80, %a<br>
+ %cmp = icmp ne i8 %shr, 5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_exactdiv<br>
+; CHECK-NEXT: icmp eq i8 %a, 4<br>
+define i1 @nonexact_lshr_eq_exactdiv(i8 %a) {<br>
+ %shr = lshr i8 80, %a<br>
+ %cmp = icmp eq i8 %shr, 5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_exactdiv<br>
+; CHECK-NEXT: icmp ne i8 %a, 4<br>
+define i1 @nonexact_lshr_ne_exactdiv(i8 %a) {<br>
+ %shr = lshr i8 80, %a<br>
+ %cmp = icmp ne i8 %shr, 5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_exactdiv<br>
+; CHECK-NEXT: icmp eq i8 %a, 4<br>
+define i1 @exact_ashr_eq_exactdiv(i8 %a) {<br>
+ %shr = ashr exact i8 -80, %a<br>
+ %cmp = icmp eq i8 %shr, -5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_exactdiv<br>
+; CHECK-NEXT: icmp ne i8 %a, 4<br>
+define i1 @exact_ashr_ne_exactdiv(i8 %a) {<br>
+ %shr = ashr exact i8 -80, %a<br>
+ %cmp = icmp ne i8 %shr, -5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_exactdiv<br>
+; CHECK-NEXT: icmp eq i8 %a, 4<br>
+define i1 @nonexact_ashr_eq_exactdiv(i8 %a) {<br>
+ %shr = ashr i8 -80, %a<br>
+ %cmp = icmp eq i8 %shr, -5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_exactdiv<br>
+; CHECK-NEXT: icmp ne i8 %a, 4<br>
+define i1 @nonexact_ashr_ne_exactdiv(i8 %a) {<br>
+ %shr = ashr i8 -80, %a<br>
+ %cmp = icmp ne i8 %shr, -5<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_noexactdiv<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_lshr_eq_noexactdiv(i8 %a) {<br>
+ %shr = lshr exact i8 80, %a<br>
+ %cmp = icmp eq i8 %shr, 31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_noexactdiv<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_lshr_ne_noexactdiv(i8 %a) {<br>
+ %shr = lshr exact i8 80, %a<br>
+ %cmp = icmp ne i8 %shr, 31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_noexactdiv<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_lshr_eq_noexactdiv(i8 %a) {<br>
+ %shr = lshr i8 80, %a<br>
+ %cmp = icmp eq i8 %shr, 31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_noexactdiv<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_lshr_ne_noexactdiv(i8 %a) {<br>
+ %shr = lshr i8 80, %a<br>
+ %cmp = icmp ne i8 %shr, 31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_noexactdiv<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_eq_noexactdiv(i8 %a) {<br>
+ %shr = ashr exact i8 -80, %a<br>
+ %cmp = icmp eq i8 %shr, -31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_noexactdiv<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_ne_noexactdiv(i8 %a) {<br>
+ %shr = ashr exact i8 -80, %a<br>
+ %cmp = icmp ne i8 %shr, -31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_noexactdiv<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_ashr_eq_noexactdiv(i8 %a) {<br>
+ %shr = ashr i8 -80, %a<br>
+ %cmp = icmp eq i8 %shr, -31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_noexactdiv<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_ashr_ne_noexactdiv(i8 %a) {<br>
+ %shr = ashr i8 -80, %a<br>
+ %cmp = icmp ne i8 %shr, -31<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_eq_noexactlog<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_lshr_eq_noexactlog(i8 %a) {<br>
+ %shr = lshr exact i8 90, %a<br>
+ %cmp = icmp eq i8 %shr, 30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_lshr_ne_noexactlog<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_lshr_ne_noexactlog(i8 %a) {<br>
+ %shr = lshr exact i8 90, %a<br>
+ %cmp = icmp ne i8 %shr, 30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_eq_noexactlog<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_lshr_eq_noexactlog(i8 %a) {<br>
+ %shr = lshr i8 90, %a<br>
+ %cmp = icmp eq i8 %shr, 30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_lshr_ne_noexactlog<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_lshr_ne_noexactlog(i8 %a) {<br>
+ %shr = lshr i8 90, %a<br>
+ %cmp = icmp ne i8 %shr, 30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_eq_noexactlog<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @exact_ashr_eq_noexactlog(i8 %a) {<br>
+ %shr = ashr exact i8 -90, %a<br>
+ %cmp = icmp eq i8 %shr, -30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @exact_ashr_ne_noexactlog<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @exact_ashr_ne_noexactlog(i8 %a) {<br>
+ %shr = ashr exact i8 -90, %a<br>
+ %cmp = icmp ne i8 %shr, -30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_eq_noexactlog<br>
+; CHECK-NEXT: ret i1 false<br>
+define i1 @nonexact_ashr_eq_noexactlog(i8 %a) {<br>
+ %shr = ashr i8 -90, %a<br>
+ %cmp = icmp eq i8 %shr, -30<br>
+ ret i1 %cmp<br>
+}<br>
+<br>
+; CHECK-LABEL: @nonexact_ashr_ne_noexactlog<br>
+; CHECK-NEXT: ret i1 true<br>
+define i1 @nonexact_ashr_ne_noexactlog(i8 %a) {<br>
+ %shr = ashr i8 -90, %a<br>
+ %cmp = icmp ne i8 %shr, -30<br>
+ ret i1 %cmp<br>
+}<br>
<br>
<br>
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</blockquote></div><br></div>