[PATCH] ARM: add support for QBIT

[Saleem Abdulrasool]

Hi t.p.northover, kongyi, rengolin,

Add support for the __ARM_FEATURE_QBIT preprocessor macro.  Also add associated
intrinsics for checking the state of the Q flag.  This is supported on ARMv5
variant 'e' and later CPUs.  These implement section 6.4.6 and 9.1.1 of the
ACLE.

http://reviews.llvm.org/D6107

Files:
  lib/Basic/Targets.cpp
  lib/Headers/arm_acle.h
  test/Preprocessor/arm-acle-6.4.c

Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -4050,6 +4050,11 @@
     return ArchName.endswith("v6t2") || ArchName.endswith("v7") ||
            ArchName.endswith("v8") || CPUArch == "6T2" || CPUArchVer >= 7;
   }
+  bool hasQFlag(StringRef ArchName, unsigned CPUArchVer) const {
+    // ARMv5 variant 'e' and later have bit[27] of the CPSR defined as the Q bit
+    return CPUArchVer > 5 || ArchName.endswith("v5e") ||
+           ArchName.endswith("v5te");
+  }
   void getTargetDefines(const LangOptions &Opts,
                         MacroBuilder &Builder) const override {
     // Target identification.
@@ -4096,6 +4101,10 @@
 
     // ACLE 6.4.2 Architectural Profile (A, R, M or pre-Cortex)
 
+    // ACLE 6.4.6 Q (saturation) flag
+    if (hasQFlag(ArchName, CPUArchVer))
+      Builder.defineMacro("__ARM_FEATURE_QBIT", "1");
+
     // __ARM_ARCH_PROFILE is defined as 'A', 'R', 'M' or 'S', or unset.
     if (!CPUProfile.empty())
       Builder.defineMacro("__ARM_ARCH_PROFILE", "'" + CPUProfile + "'");
Index: lib/Headers/arm_acle.h
===================================================================
--- lib/Headers/arm_acle.h
+++ lib/Headers/arm_acle.h
@@ -107,6 +107,25 @@
 }
 
 /* 9 DATA-PROCESSING INTRINSICS */
+
+/* 9.1.1 The Q (saturation) flag */
+static __inline__ int __attribute__((always_inline, nodebug))
+__saturation_occurred(void) {
+  uint32_t cpsr;
+  __asm__ __volatile__("mrs %0, cpsr" : "=r"(cpsr));
+  return cpsr & 0x08000000;
+}
+
+static __inline__ void __attribute__((always_inline, nodebug))
+__set_saturation_occurred(int occurred) {
+  __asm__ __volatile__ ("msr cpsr_q, %0" : : "r" (occurred));
+}
+
+static __inline__ void __attribute__((always_inline, nodebug))
+__ignore_saturation(void) {
+  /* not yet implemented */
+}
+
 /* 9.2 Miscellaneous data-processing intrinsics */
 /* ROR */
 static __inline__ uint32_t __attribute__((always_inline, nodebug))
Index: test/Preprocessor/arm-acle-6.4.c
===================================================================
--- test/Preprocessor/arm-acle-6.4.c
+++ test/Preprocessor/arm-acle-6.4.c
@@ -5,6 +5,7 @@
 // CHECK-CORTEX-M0-NOT: __ARM_ARCH_ISA_ARM
 // CHECK-CORTEX-M0: __ARM_ARCH_ISA_THUMB 1
 // CHECK-CORTEX-M0: __ARM_ARCH_PROFILE 'M'
+// CHECK-CORTEX-M0: __ARM_FEATURE_QBIT 1
 // CHECK-CORTEX-M0-NOT: __ARM_FEATURE_NUMERIC_MAXMIN
 // CHECK-CORTEX-M0-NOT: __ARM_FEATURE_DIRECTED_ROUNDING
 
@@ -15,6 +16,7 @@
 // CHECK-ARM810: __ARM_ARCH_ISA_ARM 1
 // CHECK-ARM810-NOT: __ARM_ARCH_ISA_THUMB
 // CHECK-ARM810-NOT: __ARM_ARCH_PROFILE
+// CHECK-ARM810-NOT: __ARM_FEATURE_QBIT
 // CHECK-ARM810-NOT: __ARM_FEATURE_NUMERIC_MAXMIN
 // CHECK-ARM810-NOT: __ARM_FEATURE_DIRECTED_ROUNDING
 
@@ -25,6 +27,7 @@
 // CHECK-ARM7TDMI: __ARM_ARCH_ISA_ARM 1
 // CHECK-ARM7TDMI: __ARM_ARCH_ISA_THUMB 1
 // CHECK-ARM7TDMI-NOT: __ARM_ARCH_PROFILE
+// CHECK-ARM7TDMI-NOT: __ARM_FEATURE_QBIT
 
 // RUN: %clang -target arm-eabi -mcpu=cortex-a7 -x c -E -dM %s -o - | FileCheck %s -check-prefix CHECK-CORTEX-A7
 
@@ -33,6 +36,7 @@
 // CHECK-CORTEX-A7: __ARM_ARCH_ISA_ARM 1
 // CHECK-CORTEX-A7: __ARM_ARCH_ISA_THUMB 2
 // CHECK-CORTEX-A7: __ARM_ARCH_PROFILE 'A'
+// CHECK-CORTEX-A7: __ARM_FEATURE_QBIT
 // CHECK-CORTEX-A7-NOT: __ARM_FEATURE_NUMERIC_MAXMIN
 // CHECK-CORTEX-A7-NOT: __ARM_FEATURE_DIRECTED_ROUNDING
 
@@ -43,4 +47,13 @@
 // CHECK-CORTEX-R4: __ARM_ARCH_ISA_ARM 1
 // CHECK-CORTEX-R4: __ARM_ARCH_ISA_THUMB 2
 // CHECK-CORTEX-R4: __ARM_ARCH_PROFILE 'R'
+// CHECK-CORTEX-R4: __ARM_FEATURE_QBIT
+
+// RUN: %clang -target arm-eabi -mcpu=arm10tdmi -x c -E -dM %s -o - | FileCheck %s -check-prefix CHECK-ARMv5
+
+// CHECK-ARMv5-NOT: __ARM_FEATURE_QBIT
+
+// RUN: %clang -target arm-eabi -mcpu=arm10e -x c -E -dM %s -o - | FileCheck %s -check-prefix CHECK-ARMv5TE
+
+// CHECK-ARMv5TE: __ARM_FEATURE_QBIT
 

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