From ffdbd2a06ca2a2703647fb87140b8965b3b0218c Mon Sep 17 00:00:00 2001
From: Johannes Doerfert <johannes@jdoerfert.de>
Date: Sun, 9 Feb 2020 19:07:30 -0600
Subject: [Attributor] Look through (some) casts in
 AAValueConstantRangeFloating

Casts can be handled natively by the ConstantRange class. We do limit it
to extends for now as we assume an integer type in different locations.
A TODO and a test case with a FIXME was added to remove that restriction
in the future.
---
 llvm/lib/Transforms/IPO/Attributor.cpp | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'llvm/lib')

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 8b97e3d..f16b9bc 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -6183,6 +6183,12 @@ struct AAValueConstantRangeFloating : AAValueConstantRangeImpl {
         return;
       }
 
+    // We handle casts in the updateImpl.
+    // TODO: Allow non integers as well.
+    if (CastInst *CI = dyn_cast<CastInst>(&V))
+      if (CI->getOperand(0)->getType()->isIntegerTy())
+        return;
+
     // Otherwise we give up.
     indicatePessimisticFixpoint();
 
@@ -6212,6 +6218,20 @@ struct AAValueConstantRangeFloating : AAValueConstantRangeImpl {
     return T.isValidState();
   }
 
+  bool calculateCastInst(Attributor &A, CastInst *CastI, IntegerRangeState &T,
+                         Instruction *CtxI) {
+    assert(CastI->getNumOperands() == 1 && "Expected cast to be unary!");
+    // TODO: Allow non integers as well.
+    Value &OpV = *CastI->getOperand(0);
+    assert(OpV.getType()->isIntegerTy() && "Expected integer cast");
+
+    auto &OpAA =
+        A.getAAFor<AAValueConstantRange>(*this, IRPosition::value(OpV));
+    T.unionAssumed(
+        OpAA.getAssumed().castOp(CastI->getOpcode(), getState().getBitWidth()));
+    return T.isValidState();
+  }
+
   bool calculateCmpInst(Attributor &A, CmpInst *CmpI, IntegerRangeState &T,
                         Instruction *CtxI) {
     Value *LHS = CmpI->getOperand(0);
@@ -6282,6 +6302,8 @@ struct AAValueConstantRangeFloating : AAValueConstantRangeImpl {
         return calculateBinaryOperator(A, BinOp, T, CtxI);
       else if (auto *CmpI = dyn_cast<CmpInst>(I))
         return calculateCmpInst(A, CmpI, T, CtxI);
+      else if (auto *CastI = dyn_cast<CastInst>(I))
+        return calculateCastInst(A, CastI, T, CtxI);
       else {
         // Give up with other instructions.
         // TODO: Add other instructions
-- 
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