The most common simplification missed by instsimplify in unoptimized bitcode
is "X != 0 -> X" when X is a boolean. This occurs a lot because of the way
llvm-gcc converts gcc's conditional expressions. Add this, and a few other
similar transforms for completeness.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123372 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 030d61a..b3a3aca 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -938,8 +938,8 @@
Pred = CmpInst::getSwappedPredicate(Pred);
}
- // ITy - This is the return type of the compare we're considering.
- const Type *ITy = GetCompareTy(LHS);
+ const Type *ITy = GetCompareTy(LHS); // The return type.
+ const Type *OpTy = LHS->getType(); // The operand type.
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
@@ -947,6 +947,83 @@
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
+ // Special case logic when the operands have i1 type.
+ if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
+ cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_EQ:
+ // X == 1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_NE:
+ // X != 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_UGT:
+ // X >u 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_UGE:
+ // X >=u 1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_SLT:
+ // X <s 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_SLE:
+ // X <=s -1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ }
+ }
+
+ // See if we are doing a comparison with a constant.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_UGT:
+ if (CI->isMaxValue(false)) // A >u MAX -> FALSE
+ return ConstantInt::getFalse(CI->getContext());
+ break;
+ case ICmpInst::ICMP_UGE:
+ if (CI->isMinValue(false)) // A >=u MIN -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_ULT:
+ if (CI->isMinValue(false)) // A <u MIN -> FALSE
+ return ConstantInt::getFalse(CI->getContext());
+ break;
+ case ICmpInst::ICMP_ULE:
+ if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SGT:
+ if (CI->isMaxValue(true)) // A >s MAX -> FALSE
+ return ConstantInt::getFalse(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SGE:
+ if (CI->isMinValue(true)) // A >=s MIN -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SLT:
+ if (CI->isMinValue(true)) // A <s MIN -> FALSE
+ return ConstantInt::getFalse(CI->getContext());
+ break;
+ case ICmpInst::ICMP_SLE:
+ if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
+ return ConstantInt::getTrue(CI->getContext());
+ break;
+ }
+ }
+
// icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
// addresses never equal each other! We already know that Op0 != Op1.
if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
@@ -955,32 +1032,6 @@
isa<ConstantPointerNull>(RHS)))
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
- // See if we are doing a comparison with a constant.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
- // If we have an icmp le or icmp ge instruction, turn it into the
- // appropriate icmp lt or icmp gt instruction. This allows us to rely on
- // them being folded in the code below.
- switch (Pred) {
- default: break;
- case ICmpInst::ICMP_ULE:
- if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
- return ConstantInt::getTrue(CI->getContext());
- break;
- case ICmpInst::ICMP_SLE:
- if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
- return ConstantInt::getTrue(CI->getContext());
- break;
- case ICmpInst::ICMP_UGE:
- if (CI->isMinValue(false)) // A >=u MIN -> TRUE
- return ConstantInt::getTrue(CI->getContext());
- break;
- case ICmpInst::ICMP_SGE:
- if (CI->isMinValue(true)) // A >=s MIN -> TRUE
- return ConstantInt::getTrue(CI->getContext());
- break;
- }
- }
-
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))