[llvm-commits] [llvm] r123372 - in /llvm/trunk: lib/Analysis/InstructionSimplify.cpp test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll
Duncan Sands
baldrick at free.fr
Thu Jan 13 00:56:29 PST 2011
Author: baldrick
Date: Thu Jan 13 02:56:29 2011
New Revision: 123372
URL: http://llvm.org/viewvc/llvm-project?rev=123372&view=rev
Log:
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.
Modified:
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll
Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=123372&r1=123371&r2=123372&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Thu Jan 13 02:56:29 2011
@@ -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
@@ -947,40 +947,91 @@
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
- // 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) ||
- isa<ConstantPointerNull>(LHS)) &&
- (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
- isa<ConstantPointerNull>(RHS)))
- return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(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)) {
- // 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());
+ 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) ||
+ isa<ConstantPointerNull>(LHS)) &&
+ (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
+ isa<ConstantPointerNull>(RHS)))
+ return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+
// 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))
Modified: llvm/trunk/test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll?rev=123372&r1=123371&r2=123372&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/2010-12-20-I1Arithmetic.ll Thu Jan 13 02:56:29 2011
@@ -20,3 +20,10 @@
ret i1 %z
; CHECK: ret i1 %x
}
+
+define i1 @ne(i1 %x) {
+; CHECK: @ne
+ %z = icmp ne i1 %x, 0
+ ret i1 %z
+; CHECK: ret i1 %x
+}
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