From 1e1db800487cbaf96e8f7809e3df42ba979c121d Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Tue, 10 Sep 2019 21:12:29 +0000
Subject: [PATCH] [ValueTracking] Factor our common speculation suppression
 logic [NFC]

Expose a utility function so that all places which want to suppress speculation (when otherwise legal) due to ordering and/or sanitizer interaction can do so.

llvm-svn: 371556
---
 llvm/include/llvm/Analysis/ValueTracking.h            |  7 +++++++
 llvm/lib/Analysis/ValueTracking.cpp                   | 19 +++++++++++++------
 .../Vectorize/LoopVectorizationLegality.cpp           | 15 ---------------
 3 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 1616ef4..0a3fab3 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -384,6 +384,13 @@ class Value;
   /// Return true if the only users of this pointer are lifetime markers.
   bool onlyUsedByLifetimeMarkers(const Value *V);
 
+  /// Return true if speculation of the given load must be suppressed to avoid
+  /// ordering or interfering with an active sanitizer.  If not suppressed,
+  /// dereferenceability and alignment must be proven separately.  Note: This
+  /// is only needed for raw reasoning; if you use the interface below
+  /// (isSafeToSpeculativelyExecute), this is handled internally.
+  bool mustSuppressSpeculation(const LoadInst &LI);
+
   /// Return true if the instruction does not have any effects besides
   /// calculating the result and does not have undefined behavior.
   ///
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index a8ee594..55c3e02 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3877,6 +3877,18 @@ bool llvm::onlyUsedByLifetimeMarkers(const Value *V) {
   return true;
 }
 
+bool llvm::mustSuppressSpeculation(const LoadInst &LI) {
+  if (!LI.isUnordered())
+    return true;
+  const Function &F = *LI.getFunction();
+  // Speculative load may create a race that did not exist in the source.
+  return F.hasFnAttribute(Attribute::SanitizeThread) ||
+    // Speculative load may load data from dirty regions.
+    F.hasFnAttribute(Attribute::SanitizeAddress) ||
+    F.hasFnAttribute(Attribute::SanitizeHWAddress);
+}
+
+
 bool llvm::isSafeToSpeculativelyExecute(const Value *V,
                                         const Instruction *CtxI,
                                         const DominatorTree *DT) {
@@ -3921,12 +3933,7 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
   }
   case Instruction::Load: {
     const LoadInst *LI = cast<LoadInst>(Inst);
-    if (!LI->isUnordered() ||
-        // Speculative load may create a race that did not exist in the source.
-        LI->getFunction()->hasFnAttribute(Attribute::SanitizeThread) ||
-        // Speculative load may load data from dirty regions.
-        LI->getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
-        LI->getFunction()->hasFnAttribute(Attribute::SanitizeHWAddress))
+    if (mustSuppressSpeculation(*LI))
       return false;
     const DataLayout &DL = LI->getModule()->getDataLayout();
     return isDereferenceableAndAlignedPointer(LI->getPointerOperand(),
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
index fe1e978..3b3e055 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -969,21 +969,6 @@ static bool isDereferenceableAndAlignedInLoop(LoadInst *LI, Loop *L,
                                             DL, HeaderFirstNonPHI, &DT);
 }
 
-/// Return true if speculation of the given load must be suppressed for
-/// correctness reasons.  If not suppressed, dereferenceability and alignment
-/// must be proven.
-/// TODO: Move to ValueTracking.h/cpp in a separate change
-static bool mustSuppressSpeculation(const LoadInst &LI) {
-  if (!LI.isUnordered())
-    return true;
-  const Function &F = *LI.getFunction();
-  // Speculative load may create a race that did not exist in the source.
-  return F.hasFnAttribute(Attribute::SanitizeThread) ||
-    // Speculative load may load data from dirty regions.
-    F.hasFnAttribute(Attribute::SanitizeAddress) ||
-    F.hasFnAttribute(Attribute::SanitizeHWAddress);
-}
-
 bool LoopVectorizationLegality::canVectorizeWithIfConvert() {
   if (!EnableIfConversion) {
     reportVectorizationFailure("If-conversion is disabled",
-- 
2.7.4