From: Hal Finkel <hfinkel@anl.gov>
Date: Fri, 25 Jul 2014 21:45:17 +0000 (+0000)
Subject: Canonicalization for @llvm.assume
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=5cb8ab5b5af971ee589f2659529a5759378c76ad;p=oota-llvm.git

Canonicalization for @llvm.assume

Adds simple logical canonicalization of assumption intrinsics to instcombine,
currently:
 - invariant(a && b) -> invariant(a); invariant(b)
 - invariant(!(a || b)) -> invariant(!a); invariant(!b)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213977 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 658178d5914..8523c734549 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -994,6 +994,23 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
       return EraseInstFromFunction(CI);
     break;
   }
+  case Intrinsic::assume: {
+    // Canonicalize assume(a && b) -> assume(a); assume(b);
+    Value *IIOperand = II->getArgOperand(0), *A, *B,
+          *AssumeIntrinsic = II->getCalledValue();
+    if (match(IIOperand, m_And(m_Value(A), m_Value(B)))) {
+      Builder->CreateCall(AssumeIntrinsic, A, II->getName());
+      Builder->CreateCall(AssumeIntrinsic, B, II->getName());
+      return EraseInstFromFunction(*II);
+    }
+    // assume(!(a || b)) -> assume(!a); assume(!b);
+    if (match(IIOperand, m_Not(m_Or(m_Value(A), m_Value(B))))) {
+      Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(A), II->getName());
+      Builder->CreateCall(AssumeIntrinsic, Builder->CreateNot(B), II->getName());
+      return EraseInstFromFunction(*II);
+    }
+    break;
+  }
   }
 
   return visitCallSite(II);
diff --git a/test/Transforms/InstCombine/assume.ll b/test/Transforms/InstCombine/assume.ll
new file mode 100644
index 00000000000..d65a8f7bc5e
--- /dev/null
+++ b/test/Transforms/InstCombine/assume.ll
@@ -0,0 +1,43 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind
+declare void @llvm.assume(i1) #1
+
+; Function Attrs: nounwind uwtable
+define i32 @can1(i1 %a, i1 %b, i1 %c) {
+entry:
+  %and1 = and i1 %a, %b
+  %and  = and i1 %and1, %c
+  tail call void @llvm.assume(i1 %and)
+
+; CHECK-LABEL: @can1
+; CHECK: call void @llvm.assume(i1 %a)
+; CHECK: call void @llvm.assume(i1 %b)
+; CHECK: call void @llvm.assume(i1 %c)
+; CHECK: ret i32
+
+  ret i32 5
+}
+
+; Function Attrs: nounwind uwtable
+define i32 @can2(i1 %a, i1 %b, i1 %c) {
+entry:
+  %v = or i1 %a, %b
+  %w = xor i1 %v, 1
+  tail call void @llvm.assume(i1 %w)
+
+; CHECK-LABEL: @can2
+; CHECK: %[[V1:[^ ]+]] = xor i1 %a, true
+; CHECK: call void @llvm.assume(i1 %[[V1]])
+; CHECK: %[[V2:[^ ]+]] = xor i1 %b, true
+; CHECK: call void @llvm.assume(i1 %[[V2]])
+; CHECK: ret i32
+
+  ret i32 5
+}
+
+attributes #0 = { nounwind uwtable }
+attributes #1 = { nounwind }
+