[llvm] r206913 - [Constant Hoisting] Materialize the constant before the cloned cast instruction.

[Juergen Ributzka]

Author: ributzka
Date: Tue Apr 22 13:06:58 2014
New Revision: 206913

URL: http://llvm.org/viewvc/llvm-project?rev=206913&view=rev
Log:
[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>

Added:
    llvm/trunk/test/Transforms/ConstantHoisting/X86/cast-inst.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/ConstantHoisting.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/ConstantHoisting.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ConstantHoisting.cpp?rev=206913&r1=206912&r2=206913&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ConstantHoisting.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ConstantHoisting.cpp Tue Apr 22 13:06:58 2014
@@ -207,7 +207,16 @@ bool ConstantHoisting::runOnFunction(Fun
 /// \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 Constan
   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();

Added: llvm/trunk/test/Transforms/ConstantHoisting/X86/cast-inst.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ConstantHoisting/X86/cast-inst.ll?rev=206913&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ConstantHoisting/X86/cast-inst.ll (added)
+++ llvm/trunk/test/Transforms/ConstantHoisting/X86/cast-inst.ll Tue Apr 22 13:06:58 2014
@@ -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
+}
+