From 61378363b76ad84dc7effff506d7c3e991225743 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Mon, 2 Aug 2010 09:32:13 +0000
Subject: [PATCH] Re-apply the infamous r108614, with a fix pointed out by Dirk
 Steinke.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110036 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstCombineAndOrXor.cpp       | 43 ++++++++++++++++---
 test/Transforms/InstCombine/bit-checks.ll     | 26 +++++++++++
 2 files changed, 64 insertions(+), 5 deletions(-)
 create mode 100644 test/Transforms/InstCombine/bit-checks.ll

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 3f4a857c41a..19a05bfe9bb 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -472,6 +472,22 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
       Value *NewOr = Builder->CreateOr(Val, Val2);
       return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
     }
+    
+    // (icmp ne (A & C1), 0) & (icmp ne (A & C2), 0) -->
+    // (icmp eq (A & (C1|C2)), (C1|C2)) where C1 and C2 are non-zero POT
+    if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
+      Value *Op1 = 0, *Op2 = 0;
+      ConstantInt *CI1 = 0, *CI2 = 0;
+      if (match(LHS->getOperand(0), m_And(m_Value(Op1), m_ConstantInt(CI1))) &&
+          match(RHS->getOperand(0), m_And(m_Value(Op2), m_ConstantInt(CI2)))) {
+        if (Op1 == Op2 && !CI1->isZero() && !CI2->isZero() &&
+            CI1->getValue().isPowerOf2() && CI2->getValue().isPowerOf2()) {
+          Constant *ConstOr = ConstantExpr::getOr(CI1, CI2);
+          Value *NewAnd = Builder->CreateAnd(Op1, ConstOr);
+          return Builder->CreateICmp(ICmpInst::ICMP_EQ, NewAnd, ConstOr);
+        }
+      }
+    }
   }
   
   // From here on, we only handle:
@@ -1151,11 +1167,28 @@ Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
   ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
   if (LHSCst == 0 || RHSCst == 0) return 0;
 
-  // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
-  if (LHSCst == RHSCst && LHSCC == RHSCC &&
-      LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
-    Value *NewOr = Builder->CreateOr(Val, Val2);
-    return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
+  if (LHSCst == RHSCst && LHSCC == RHSCC) {
+    // (icmp ne A, 0) | (icmp ne B, 0) --> (icmp ne (A|B), 0)
+    if (LHSCC == ICmpInst::ICMP_NE && LHSCst->isZero()) {
+      Value *NewOr = Builder->CreateOr(Val, Val2);
+      return Builder->CreateICmp(LHSCC, NewOr, LHSCst);
+    }
+  
+    // (icmp eq (A & C1), 0) | (icmp eq (A & C2), 0) -->
+    // (icmp ne (A & (C1|C2)), (C1|C2)) where C1 and C2 are non-zero POT
+    if (LHSCC == ICmpInst::ICMP_EQ && LHSCst->isZero()) {
+      Value *Op1 = 0, *Op2 = 0;
+      ConstantInt *CI1 = 0, *CI2 = 0;
+      if (match(LHS->getOperand(0), m_And(m_Value(Op1), m_ConstantInt(CI1))) &&
+          match(RHS->getOperand(0), m_And(m_Value(Op2), m_ConstantInt(CI2)))) {
+        if (Op1 == Op2 && !CI1->isZero() && !CI2->isZero() &&
+            CI1->getValue().isPowerOf2() && CI2->getValue().isPowerOf2()) {
+          Constant *ConstOr = ConstantExpr::getOr(CI1, CI2);
+          Value *NewAnd = Builder->CreateAnd(Op1, ConstOr);
+          return Builder->CreateICmp(ICmpInst::ICMP_NE, NewAnd, ConstOr);
+        }
+      }
+    }
   }
   
   // From here on, we only handle:
diff --git a/test/Transforms/InstCombine/bit-checks.ll b/test/Transforms/InstCombine/bit-checks.ll
new file mode 100644
index 00000000000..d774c0972de
--- /dev/null
+++ b/test/Transforms/InstCombine/bit-checks.ll
@@ -0,0 +1,26 @@
+; This test makes sure that these instructions are properly eliminated.
+;
+; RUN: opt < %s -instcombine -S | \
+; RUN:    not grep {tobool}
+; END.
+define i32 @main(i32 %argc, i8** %argv) nounwind ssp {
+entry:
+  %and = and i32 %argc, 1                         ; <i32> [#uses=1]
+  %tobool = icmp ne i32 %and, 0                   ; <i1> [#uses=1]
+  %and2 = and i32 %argc, 2                        ; <i32> [#uses=1]
+  %tobool3 = icmp ne i32 %and2, 0                 ; <i1> [#uses=1]
+  %or.cond = and i1 %tobool, %tobool3             ; <i1> [#uses=1]
+  %retval.0 = select i1 %or.cond, i32 2, i32 1    ; <i32> [#uses=1]
+  ret i32 %retval.0
+}
+
+define i32 @main2(i32 %argc, i8** nocapture %argv) nounwind readnone ssp {
+entry:
+  %and = and i32 %argc, 1                         ; <i32> [#uses=1]
+  %tobool = icmp eq i32 %and, 0                   ; <i1> [#uses=1]
+  %and2 = and i32 %argc, 2                        ; <i32> [#uses=1]
+  %tobool3 = icmp eq i32 %and2, 0                 ; <i1> [#uses=1]
+  %or.cond = or i1 %tobool, %tobool3              ; <i1> [#uses=1]
+  %storemerge = select i1 %or.cond, i32 0, i32 1  ; <i32> [#uses=1]
+  ret i32 %storemerge
+}
\ No newline at end of file