[llvm] [NFC][Load] Find better place for `mustSuppressSpeculation` (PR #100794)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: Vitaly Buka (vitalybuka)

<details>
<summary>Changes</summary>

And extract `suppressSpeculativeLoadForSanitizers`.


---
Full diff: https://github.com/llvm/llvm-project/pull/100794.diff


4 Files Affected:

- (modified) llvm/include/llvm/Analysis/Loads.h (+7) 
- (modified) llvm/include/llvm/Analysis/ValueTracking.h (-7) 
- (modified) llvm/lib/Analysis/Loads.cpp (+15) 
- (modified) llvm/lib/Analysis/ValueTracking.cpp (-11) 


``````````diff
diff --git a/llvm/include/llvm/Analysis/Loads.h b/llvm/include/llvm/Analysis/Loads.h
index 33e817828b754..38f86f77b4158 100644
--- a/llvm/include/llvm/Analysis/Loads.h
+++ b/llvm/include/llvm/Analysis/Loads.h
@@ -106,6 +106,13 @@ bool isSafeToLoadUnconditionally(Value *V, Type *Ty, Align Alignment,
                                  const DominatorTree *DT = nullptr,
                                  const TargetLibraryInfo *TLI = nullptr);
 
+/// 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);
+
 /// The default number of maximum instructions to scan in the block, used by
 /// FindAvailableLoadedValue().
 extern cl::opt<unsigned> DefMaxInstsToScan;
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 5ef6e43483906..96fa16970584d 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -792,13 +792,6 @@ bool onlyUsedByLifetimeMarkers(const Value *V);
 /// droppable instructions.
 bool onlyUsedByLifetimeMarkersOrDroppableInsts(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/Loads.cpp b/llvm/lib/Analysis/Loads.cpp
index 61c6aa5e5a3eb..e2ab425bbdc03 100644
--- a/llvm/lib/Analysis/Loads.cpp
+++ b/llvm/lib/Analysis/Loads.cpp
@@ -345,6 +345,21 @@ bool llvm::isDereferenceableAndAlignedInLoop(LoadInst *LI, Loop *L,
                                             HeaderFirstNonPHI, AC, &DT);
 }
 
+static bool suppressSpeculativeLoadForSanitizers(const Function &F) {
+  // 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::mustSuppressSpeculation(const LoadInst &LI) {
+  if (!LI.isUnordered())
+    return true;
+  const Function &F = *LI.getFunction();
+  return suppressSpeculativeLoadForSanitizers(F);
+}
+
 /// Check if executing a load of this pointer value cannot trap.
 ///
 /// If DT and ScanFrom are specified this method performs context-sensitive
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index bfd26fadd237b..497f6eafd22d8 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -6798,17 +6798,6 @@ bool llvm::onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V) {
       V, /* AllowLifetime */ true, /* AllowDroppable */ 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 Instruction *Inst,
                                         const Instruction *CtxI,
                                         AssumptionCache *AC,

``````````

</details>


https://github.com/llvm/llvm-project/pull/100794