[ARM] Allow execute only code on Cortex-m23

The NoMovt feature prevents the use of MOVW/MOVT
instructions on Cortex-M23 for performance reasons.
These instructions are required for execute only code
so NoMovt should be disabled when that option is enabled.

Differential Revision: https://reviews.llvm.org/D52551

llvm-svn: 343302

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index 1c17b63a35d..b1d0761e323 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -188,8 +188,10 @@ void ARMSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
   assert(hasV6T2Ops() || !hasThumb2());
 
   // Execute only support requires movt support
-  if (genExecuteOnly())
-    assert(hasV8MBaselineOps() && !NoMovt && "Cannot generate execute-only code for this target");
+  if (genExecuteOnly()) {
+    NoMovt = false;
+    assert(hasV8MBaselineOps() && "Cannot generate execute-only code for this target");
+  }
 
   // Keep a pointer to static instruction cost data for the specified CPU.
   SchedModel = getSchedModelForCPU(CPUString);