[Xtensa] Disable hardware loops by default.

Disable hwloop by default and fix hwloop tests.

Author: andreisfr

llvm/lib/Target/Xtensa/XtensaTargetTransformInfo.cpp

@@ -13,7 +13,7 @@ using namespace llvm;
 #define DEBUG_TYPE "xtensatti"
 
 static cl::opt<bool> DisableLowOverheadLoops(
-    "disable-xtensa-hwloops", cl::Hidden, cl::init(false),
+    "disable-xtensa-hwloops", cl::Hidden, cl::init(true),
     cl::desc("Disable the generation of hardware loops"));
 
 bool XtensaTTIImpl::isHardwareLoopProfitable(Loop *L, ScalarEvolution &SE,

llvm/test/CodeGen/Xtensa/hwloop_inner_loop.ll

@@ -1,4 +1,4 @@
-; RUN: llc -O1 -mtriple=xtensa -mcpu=esp32 %s -o - | FileCheck %s
+; RUN: llc -O1 -mtriple=xtensa -mcpu=esp32 -disable-xtensa-hwloops=false %s -o - | FileCheck %s
 
 
 ; Function Attrs: norecurse nounwind optsize readnone

llvm/test/CodeGen/Xtensa/hwloop_unsuitable_loop.ll

@@ -1,4 +1,4 @@
-; RUN: llc -O1 -mtriple=xtensa -mcpu=esp32 %s -o - | FileCheck %s
+; RUN: llc -O1 -mtriple=xtensa -mcpu=esp32 -disable-xtensa-hwloops=false %s -o - | FileCheck %s
 
 ; Function Attrs: nounwind optsize
 define i32 @test_hwloop(i32 %a, i32 %b, i32 %n) local_unnamed_addr #1 {