[SystemZ, LoopStrengthReduce]

This patch makes LSR generate better code for SystemZ in the cases of memory
intrinsics, Load->Store pairs or comparison of immediate with memory.

In order to achieve this, the following common code changes were made:

 * New TTI hook: LSRWithInstrQueries(), which defaults to false. Controls if
 LSR should do instruction-based addressing evaluations by calling
 isLegalAddressingMode() with the Instruction pointers.
 * In LoopStrengthReduce: handle address operands of memset, memmove and memcpy
 as address uses, and call isFoldableMemAccessOffset() for any LSRUse::Address,
 not just loads or stores.

SystemZ changes:

 * isLSRCostLess() implemented with Insns first, and without ImmCost.
 * New function supportedAddressingMode() that is a helper for TTI methods
 looking at Instructions passed via pointers.

Review: Ulrich Weigand, Quentin Colombet
https://reviews.llvm.org/D35262
https://reviews.llvm.org/D35049

llvm-svn: 308729

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
index 506dc742799..a4d9421e08a 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
@@ -292,6 +292,19 @@ void SystemZTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
   UP.Force = true;
 }
 
+
+bool SystemZTTIImpl::isLSRCostLess(TargetTransformInfo::LSRCost &C1,
+                                   TargetTransformInfo::LSRCost &C2) {
+  // SystemZ specific: check instruction count (first), and don't care about
+  // ImmCost, since offsets are checked explicitly.
+  return std::tie(C1.Insns, C1.NumRegs, C1.AddRecCost,
+                  C1.NumIVMuls, C1.NumBaseAdds,
+                  C1.ScaleCost, C1.SetupCost) <
+    std::tie(C2.Insns, C2.NumRegs, C2.AddRecCost,
+             C2.NumIVMuls, C2.NumBaseAdds,
+             C2.ScaleCost, C2.SetupCost);
+}
+
 unsigned SystemZTTIImpl::getNumberOfRegisters(bool Vector) {
   if (!Vector)
     // Discount the stack pointer.  Also leave out %r0, since it can't