[Analysis] Unify most of the tracking between AssumptionCache and DomConditionCache

This helps cover some missing cases in both and hopefully serves as
creating an easier framework for extending general condition based
analysis.

Author: goldsteinn

llvm/lib/Analysis/ValueTracking.cpp

@@ -9124,6 +9124,14 @@ void llvm::findValuesAffectedByCondition(
     addValueAffectedByCondition(V, InsertAffected);
   };
 
+  auto AddCmpOperands = [&AddAffected, IsAssume](Value *LHS, Value *RHS) {
+    if (IsAssume) {
+      AddAffected(LHS);
+      AddAffected(RHS);
+    } else if (match(RHS, m_Constant()))
+      AddAffected(LHS);
+  };
+
   SmallVector<Value *, 8> Worklist;
   SmallPtrSet<Value *, 8> Visited;
   Worklist.push_back(Cond);
@@ -9135,65 +9143,62 @@ void llvm::findValuesAffectedByCondition(
     CmpInst::Predicate Pred;
     Value *A, *B, *X;
 
-    if (IsAssume)
+    if (IsAssume) {
       AddAffected(V);
+      if (match(V, m_Not(m_Value(X))))
+        AddAffected(X);
+    }
+
+    if (match(V, m_LogicalOp(m_Value(A), m_Value(B)))) {
+      // assume(A && B) is split to -> assume(A); assume(B);
+      // assume(!(A || B)) is split to -> assume(!A); assume(!B);
+      // Finally, assume(A || B) / assume(!(A && B)) generally don't provide
+      // enough information to be worth handling (intersection of information as
+      // opposed to union).
+      if (!IsAssume) {
+        Worklist.push_back(A);
+        Worklist.push_back(B);
+      }
+    } else if (match(V, m_ICmp(Pred, m_Value(A), m_Value(B)))) {
+      AddCmpOperands(A, B);
+
+      if (ICmpInst::isEquality(Pred)) {
+        if (match(B, m_ConstantInt())) {
+          // (X & C) or (X | C) or (X ^ C).
+          // (X << C) or (X >>_s C) or (X >>_u C).
+          if (match(A, m_BitwiseLogic(m_Value(X), m_ConstantInt())) ||
+              match(A, m_Shift(m_Value(X), m_ConstantInt())))
+            AddAffected(X);
+        }
+      } else {
+        // Handle (A + C1) u< C2, which is the canonical form of
+        // A > C3 && A < C4.
+        if (match(A, m_Add(m_Value(X), m_ConstantInt())) &&
+            match(B, m_ConstantInt()))
+          AddAffected(X);
+
+        // Handle icmp slt/sgt (bitcast X to int), 0/-1, which is supported
+        // by computeKnownFPClass().
+        if (match(A, m_ElementWiseBitCast(m_Value(X)))) {
+          if (Pred == ICmpInst::ICMP_SLT && match(B, m_Zero()))
+            InsertAffected(X);
+          else if (Pred == ICmpInst::ICMP_SGT && match(B, m_AllOnes()))
+            InsertAffected(X);
+        }
+      }
+    } else if (match(Cond, m_FCmp(Pred, m_Value(A), m_Value(B)))) {
+      AddCmpOperands(A, B);
 
-    if (IsAssume && match(V, m_Not(m_Value(X))))
-      AddAffected(X);
-    if (!IsAssume && match(V, m_LogicalOp(m_Value(A), m_Value(B)))) {
-      Worklist.push_back(A);
-      Worklist.push_back(B);
-    } else if (match(V, m_Cmp(Pred, m_Value(A), m_Value(B))) &&
-               (IsAssume || isa<ICmpInst>(V))) {
-      if (IsAssume || match(B, m_Constant())) {
+      // fcmp fneg(x), y
+      // fcmp fabs(x), y
+      // fcmp fneg(fabs(x)), y
+      if (match(A, m_FNeg(m_Value(A))))
+        AddAffected(A);
+      if (match(A, m_FAbs(m_Value(A))))
         AddAffected(A);
-        if (IsAssume)
-          AddAffected(B);
-
-        if (IsAssume ? (Pred == ICmpInst::ICMP_EQ)
-                     : ICmpInst::isEquality(Pred)) {
-          if (match(B, m_ConstantInt())) {
-            // (X & C) or (X | C) or (X ^ C).
-            // (X << C) or (X >>_s C) or (X >>_u C).
-            if (match(A, m_BitwiseLogic(m_Value(X), m_ConstantInt())) ||
-                match(A, m_Shift(m_Value(X), m_ConstantInt())))
-              AddAffected(X);
-          }
-        } else {
-          if (Pred == ICmpInst::ICMP_NE)
-            if (match(A, m_And(m_Value(X), m_Power2())) && match(B, m_Zero()))
-              AddAffected(X);
-
-          if (!IsAssume || Pred == ICmpInst::ICMP_ULT) {
-            // Handle (A + C1) u< C2, which is the canonical form of
-            // A > C3 && A < C4.
-            if (match(A, m_Add(m_Value(X), m_ConstantInt())) &&
-                match(B, m_ConstantInt()))
-              AddAffected(X);
-          }
-          if (!IsAssume) {
-            // Handle icmp slt/sgt (bitcast X to int), 0/-1, which is supported
-            // by computeKnownFPClass().
-            if ((Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGT) &&
-                match(A, m_ElementWiseBitCast(m_Value(X))))
-              InsertAffected(X);
-          }
 
-          if (IsAssume && CmpInst::isFPPredicate(Pred)) {
-            // fcmp fneg(x), y
-            // fcmp fabs(x), y
-            // fcmp fneg(fabs(x)), y
-            if (match(A, m_FNeg(m_Value(A))))
-              AddAffected(A);
-            if (match(A, m_FAbs(m_Value(A))))
-              AddAffected(A);
-          }
-        }
-      }
-    } else if ((!IsAssume &&
-                match(Cond, m_FCmp(Pred, m_Value(A), m_Constant()))) ||
-               match(Cond, m_Intrinsic<Intrinsic::is_fpclass>(m_Value(A),
-                                                              m_Value(B)))) {
+    } else if (match(V, m_Intrinsic<Intrinsic::is_fpclass>(m_Value(A),
+                                                           m_Value()))) {
       // Handle patterns that computeKnownFPClass() support.
       AddAffected(A);
     }

llvm/test/Analysis/ValueTracking/numsignbits-from-assume.ll

@@ -51,7 +51,7 @@ define i32 @computeNumSignBits_sub1(i32 %in) {
 
 define i32 @computeNumSignBits_sub2(i32 %in) {
 ; CHECK-LABEL: @computeNumSignBits_sub2(
-; CHECK-NEXT:    [[SUB:%.*]] = add i32 [[IN:%.*]], -1
+; CHECK-NEXT:    [[SUB:%.*]] = add nsw i32 [[IN:%.*]], -1
 ; CHECK-NEXT:    [[COND:%.*]] = icmp ult i32 [[SUB]], 43
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[COND]])
 ; CHECK-NEXT:    [[SH:%.*]] = shl nuw nsw i32 [[SUB]], 3

llvm/test/Transforms/InstCombine/fpclass-from-dom-cond.ll

@@ -185,10 +185,9 @@ define i1 @test8(float %x) {
 ; CHECK-NEXT:    [[COND:%.*]] = fcmp oeq float [[ABS]], 0x7FF0000000000000
 ; CHECK-NEXT:    br i1 [[COND]], label [[IF_THEN:%.*]], label [[IF_ELSE:%.*]]
 ; CHECK:       if.then:
-; CHECK-NEXT:    [[RET1:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 575)
-; CHECK-NEXT:    ret i1 [[RET1]]
+; CHECK-NEXT:    ret i1 true
 ; CHECK:       if.else:
-; CHECK-NEXT:    [[RET2:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 575)
+; CHECK-NEXT:    [[RET2:%.*]] = call i1 @llvm.is.fpclass.f32(float [[X]], i32 59)
 ; CHECK-NEXT:    ret i1 [[RET2]]
 ;
   %abs = call float @llvm.fabs.f32(float %x)