[Constant Hoisting] Materialize the constant before the cloned cast instruction.

In the case where the constant comes from a cloned cast instruction, the
materialization code has to go before the cloned cast instruction.

This commit fixes the method that finds the materialization insertion point
by making it aware of this case.

This fixes <rdar://problem/15532441>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206913 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/ConstantHoisting.cpp b/lib/Transforms/Scalar/ConstantHoisting.cpp
index 9b7ed816ad985e5e6d5b2f91ac41691fd6db4a9e..af0450729a724314f59462cd2ed77659f2d589f3 100644 (file)
--- a/lib/Transforms/Scalar/ConstantHoisting.cpp
+++ b/lib/Transforms/Scalar/ConstantHoisting.cpp
@@ -207,7 +207,16 @@ bool ConstantHoisting::runOnFunction(Function &Fn) {
 /// \brief Find the constant materialization insertion point.
 Instruction *ConstantHoisting::findMatInsertPt(Instruction *Inst,
                                                unsigned Idx) const {
-  // The simple and common case.
+  // If the operand is a cast instruction, then we have to materialize the
+  // constant before the cast instruction.
+  if (Idx != ~0U) {
+    Value *Opnd = Inst->getOperand(Idx);
+    if (auto CastInst = dyn_cast<Instruction>(Opnd))
+      if (CastInst->isCast())
+        return CastInst;
+  }
+
+  // The simple and common case. This also includes constant expressions.
   if (!isa<PHINode>(Inst) && !isa<LandingPadInst>(Inst))
     return Inst;
 
@@ -229,7 +238,7 @@ findConstantInsertionPoint(const ConstantInfo &ConstInfo) const {
   SmallPtrSet<BasicBlock *, 8> BBs;
   for (auto const &RCI : ConstInfo.RebasedConstants)
     for (auto const &U : RCI.Uses)
-      BBs.insert(U.Inst->getParent());
+      BBs.insert(findMatInsertPt(U.Inst, U.OpndIdx)->getParent());
 
   if (BBs.count(Entry))
     return &Entry->front();

diff --git a/test/Transforms/ConstantHoisting/X86/cast-inst.ll b/test/Transforms/ConstantHoisting/X86/cast-inst.ll
new file mode 100644 (file)
index 0000000..f490f4a
--- /dev/null
+++ b/test/Transforms/ConstantHoisting/X86/cast-inst.ll
@@ -0,0 +1,29 @@
+; RUN: opt -S -consthoist < %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.9.0"
+
+; Check if the materialization of the constant and the cast instruction are
+; inserted in the correct order.
+define i32 @cast_inst_test() {
+; CHECK-LABEL:  @cast_inst_test
+; CHECK:        %const = bitcast i64 4646526064 to i64
+; CHECK:        %1 = inttoptr i64 %const to i32*
+; CHECK:        %v0 = load i32* %1, align 16
+; CHECK:        %const_mat = add i64 %const, 16
+; CHECK-NEXT:   %2 = inttoptr i64 %const_mat to i32*
+; CHECK-NEXT:   %v1 = load i32* %2, align 16
+; CHECK:        %const_mat1 = add i64 %const, 32
+; CHECK-NEXT:   %3 = inttoptr i64 %const_mat1 to i32*
+; CHECK-NEXT:   %v2 = load i32* %3, align 16
+  %a0 = inttoptr i64 4646526064 to i32*
+  %v0 = load i32* %a0, align 16
+  %a1 = inttoptr i64 4646526080 to i32*
+  %v1 = load i32* %a1, align 16
+  %a2 = inttoptr i64 4646526096 to i32*
+  %v2 = load i32* %a2, align 16
+  %r0 = add i32 %v0, %v1
+  %r1 = add i32 %r0, %v2
+  ret i32 %r1
+}
+