[llvm] 4cf70af - [GVN] Make GVN aware of aligned_alloc

[Uday Bondhugula via llvm-commits]

Author: Uday Bondhugula
Date: 2020-04-01T23:26:50+05:30
New Revision: 4cf70af94fbe910e64fa1d36cdd5bf7e46785795

URL: https://github.com/llvm/llvm-project/commit/4cf70af94fbe910e64fa1d36cdd5bf7e46785795
DIFF: https://github.com/llvm/llvm-project/commit/4cf70af94fbe910e64fa1d36cdd5bf7e46785795.diff

LOG: [GVN] Make GVN aware of aligned_alloc

Make the GVN pass aware of aligned_alloc.

Depends on D76974.

Differential Revision: https://reviews.llvm.org/D76975

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/GVN.cpp
    llvm/test/Transforms/GVN/malloc-load-removal.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index d831b0da37a5..2a6ecfcd957a 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -947,6 +947,7 @@ bool GVN::AnalyzeLoadAvailability(LoadInst *LI, MemDepResult DepInfo,
 
   // Loading the allocation -> undef.
   if (isa<AllocaInst>(DepInst) || isMallocLikeFn(DepInst, TLI) ||
+      isAlignedAllocLikeFn(DepInst, TLI) ||
       // Loading immediately after lifetime begin -> undef.
       isLifetimeStart(DepInst)) {
     Res = AvailableValue::get(UndefValue::get(LI->getType()));
@@ -1451,7 +1452,7 @@ static bool impliesEquivalanceIfFalse(CmpInst* Cmp) {
       Value *LHS = Cmp->getOperand(0);
       Value *RHS = Cmp->getOperand(1);
       // If we can prove either side non-zero, then equality must imply
-      // equivalence. 
+      // equivalence.
       // FIXME: We should do this optimization if 'no signed zeros' is
       // applicable via an instruction-level fast-math-flag or some other
       // indicator that relaxed FP semantics are being used.
@@ -1516,10 +1517,10 @@ bool GVN::processAssumeIntrinsic(IntrinsicInst *IntrinsicI) {
   // If we find an equality fact, canonicalize all dominated uses in this block
   // to one of the two values.  We heuristically choice the "oldest" of the
   // two where age is determined by value number. (Note that propagateEquality
-  // above handles the cross block case.) 
-  // 
+  // above handles the cross block case.)
+  //
   // Key case to cover are:
-  // 1) 
+  // 1)
   // %cmp = fcmp oeq float 3.000000e+00, %0 ; const on lhs could happen
   // call void @llvm.assume(i1 %cmp)
   // ret float %0 ; will change it to ret float 3.000000e+00
@@ -1560,7 +1561,7 @@ bool GVN::processAssumeIntrinsic(IntrinsicInst *IntrinsicI) {
                  << *CmpLHS << " with "
                  << *CmpRHS << " in block "
                  << IntrinsicI->getParent()->getName() << "\n");
-      
+
 
       // Setup the replacement map - this handles uses within the same block
       if (hasUsersIn(CmpLHS, IntrinsicI->getParent()))
@@ -1826,7 +1827,7 @@ void GVN::assignBlockRPONumber(Function &F) {
 bool GVN::replaceOperandsForInBlockEquality(Instruction *Instr) const {
   bool Changed = false;
   for (unsigned OpNum = 0; OpNum < Instr->getNumOperands(); ++OpNum) {
-    Value *Operand = Instr->getOperand(OpNum); 
+    Value *Operand = Instr->getOperand(OpNum);
     auto it = ReplaceOperandsWithMap.find(Operand);
     if (it != ReplaceOperandsWithMap.end()) {
       LLVM_DEBUG(dbgs() << "GVN replacing: " << *Operand << " with "
@@ -1946,7 +1947,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
 
       // If "A == B" is known true, or "A != B" is known false, then replace
       // A with B everywhere in the scope.  For floating point operations, we
-      // have to be careful since equality does not always imply equivalance.  
+      // have to be careful since equality does not always imply equivalance.
       if ((isKnownTrue && impliesEquivalanceIfTrue(Cmp)) ||
           (isKnownFalse && impliesEquivalanceIfFalse(Cmp)))
         Worklist.push_back(std::make_pair(Op0, Op1));

diff  --git a/llvm/test/Transforms/GVN/malloc-load-removal.ll b/llvm/test/Transforms/GVN/malloc-load-removal.ll
index 1d7a2ddc4c2d..84f4746344ca 100644
--- a/llvm/test/Transforms/GVN/malloc-load-removal.ll
+++ b/llvm/test/Transforms/GVN/malloc-load-removal.ll
@@ -54,3 +54,28 @@ if.end:                                           ; preds = %if.then, %entry
 ; CHECK_NO_LIBCALLS: load
 ; CHECK_NO_LIBCALLS: icmp
 }
+
+declare i8* @aligned_alloc(i64, i64) nounwind
+
+define noalias i8* @test3() nounwind uwtable ssp {
+entry:
+  %call = tail call i8* @aligned_alloc(i64 256, i64 32) nounwind
+  %0 = load i8, i8* %call, align 32
+  %tobool = icmp eq i8 %0, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  store i8 0, i8* %call, align 1
+  br label %if.end
+
+if.end:                                           ; preds = %if.then, %entry
+  ret i8* %call
+
+; CHECK-LABEL: @test3(
+; CHECK-NOT: load
+; CHECK-NOT: icmp
+
+; CHECK_NO_LIBCALLS-LABEL: @test3(
+; CHECK_NO_LIBCALLS: load
+; CHECK_NO_LIBCALLS: icmp
+}