From 26b8cd84b3c762dc6fbd7d83bebe42b3df2f8d02 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Sat, 31 May 2008 17:59:52 +0000
Subject: [PATCH] Add more i1 optimizations. add, sub, mul, s/udiv on i1 are
 now simplified away.

llvm-svn: 51817
---
 .../Scalar/InstructionCombining.cpp           | 20 ++++++++++++----
 .../InstCombine/2008-05-31-Bools.ll           | 24 +++++++++++++++++++
 2 files changed, 39 insertions(+), 5 deletions(-)
 create mode 100644 llvm/test/Transforms/InstCombine/2008-05-31-Bools.ll

diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
index 5199578b1f81..6222d2ae49bf 100644
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2551,9 +2551,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
   bool Changed = SimplifyCommutative(I);
   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
 
-  if (I.getType() == Type::Int1Ty)
-    return BinaryOperator::CreateXor(LHS, RHS);
-
   if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
     // X + undef -> undef
     if (isa<UndefValue>(RHS))
@@ -2637,8 +2634,11 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
     }
   }
 
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateXor(LHS, RHS);
+
   // X + X --> X << 1
-  if (I.getType()->isInteger() && I.getType() != Type::Int1Ty) {
+  if (I.getType()->isInteger()) {
     if (Instruction *Result = AssociativeOpt(I, AddRHS(RHS))) return Result;
 
     if (Instruction *RHSI = dyn_cast<Instruction>(RHS)) {
@@ -2976,6 +2976,9 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
         return NV;
   }
 
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateXor(Op0, Op1);
+
   if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1)) {
     if (Op1I->getOpcode() == Instruction::Add &&
         !Op0->getType()->isFPOrFPVector()) {
@@ -3170,12 +3173,15 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
     if (Value *Op1v = dyn_castNegVal(I.getOperand(1)))
       return BinaryOperator::CreateMul(Op0v, Op1v);
 
+  if (I.getType() == Type::Int1Ty)
+    return BinaryOperator::CreateAnd(Op0, I.getOperand(1));
+
   // If one of the operands of the multiply is a cast from a boolean value, then
   // we know the bool is either zero or one, so this is a 'masking' multiply.
   // See if we can simplify things based on how the boolean was originally
   // formed.
   CastInst *BoolCast = 0;
-  if (ZExtInst *CI = dyn_cast<ZExtInst>(I.getOperand(0)))
+  if (ZExtInst *CI = dyn_cast<ZExtInst>(Op0))
     if (CI->getOperand(0)->getType() == Type::Int1Ty)
       BoolCast = CI;
   if (!BoolCast)
@@ -3331,6 +3337,10 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
     if (LHS->equalsInt(0))
       return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
 
+  // It can't be division by zero, hence it must be division by one.
+  if (I.getType() == Type::Int1Ty)
+    return ReplaceInstUsesWith(I, Op0);
+
   return 0;
 }
 
diff --git a/llvm/test/Transforms/InstCombine/2008-05-31-Bools.ll b/llvm/test/Transforms/InstCombine/2008-05-31-Bools.ll
new file mode 100644
index 000000000000..f3df49b352c3
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/2008-05-31-Bools.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis > %t
+; RUN: grep {xor} %t
+; RUN: grep {and} %t
+; RUN: not grep {div} %t
+
+define i1 @foo1(i1 %a, i1 %b) {
+  %A = sub i1 %a, %b
+  ret i1 %A
+}
+
+define i1 @foo2(i1 %a, i1 %b) {
+  %A = mul i1 %a, %b
+  ret i1 %A
+}
+
+define i1 @foo3(i1 %a, i1 %b) {
+  %A = udiv i1 %a, %b
+  ret i1 %A
+}
+
+define i1 @foo4(i1 %a, i1 %b) {
+  %A = sdiv i1 %a, %b
+  ret i1 %A
+}