[PATCH] [XCore] Don't create invalid MKMSK instructions inside loadImmediate().

[Richard Osborne]

Hi robertlytton,

Previously loadImmediate() would produce MKMSK instructions with invalid
immediate values such as mkmsk r0, 9. Fix this by checking the mask size
is valid.

http://llvm-reviews.chandlerc.com/D3289

Files:
  lib/Target/XCore/XCoreInstrInfo.cpp
  test/CodeGen/XCore/epilogue_prologue.ll

Index: lib/Target/XCore/XCoreInstrInfo.cpp
===================================================================
--- lib/Target/XCore/XCoreInstrInfo.cpp
+++ lib/Target/XCore/XCoreInstrInfo.cpp
@@ -428,13 +428,21 @@
   return val < (1 << 16);
 }
 
+static bool isImmMskBitp(unsigned val) {
+  if (!isMask_32(val)) {
+    return false;
+  }
+  int N = Log2_32(val) + 1;
+  return (N >= 1 && N <= 8) || N == 16 || N == 24 || N == 32;
+}
+
 MachineBasicBlock::iterator XCoreInstrInfo::loadImmediate(
                                               MachineBasicBlock &MBB,
                                               MachineBasicBlock::iterator MI,
                                               unsigned Reg, uint64_t Value) const {
   DebugLoc dl;
   if (MI != MBB.end()) dl = MI->getDebugLoc();
-  if (isMask_32(Value)) {
+  if (isImmMskBitp(Value)) {
     int N = Log2_32(Value) + 1;
     return BuildMI(MBB, MI, dl, get(XCore::MKMSK_rus), Reg).addImm(N);
   }
Index: test/CodeGen/XCore/epilogue_prologue.ll
===================================================================
--- test/CodeGen/XCore/epilogue_prologue.ll
+++ test/CodeGen/XCore/epilogue_prologue.ll
@@ -206,28 +206,55 @@
   ret i32 %i
 }
 
+; FP + large frame: spill FP+SR+LR = entsp 2 + 256  + extsp 1
+; CHECKFP-LABEL:f8
+; CHECKFP: entsp 258
+; CHECKFP-NEXT: stw r10, sp[1]
+; CHECKFP-NEXT: ldaw r10, sp[0]
+; CHECKFP-NEXT: mkmsk [[REG:r[0-9]+]], 8
+; CHECKFP-NEXT: ldaw r0, r10{{\[}}[[REG]]{{\]}}
+; CHECKFP-NEXT: extsp 1
+; CHECKFP-NEXT: bl f5
+; CHECKFP-NEXT: ldaw sp, sp[1]
+; CHECKFP-NEXT: set sp, r10
+; CHECKFP-NEXT: ldw r10, sp[1]
+; CHECKFP-NEXT: retsp 258
+;
+; !FP + large frame: spill SR+SR+LR = entsp 3 + 256
+; CHECK-LABEL:f8
+; CHECK: entsp 257
+; CHECK-NEXT: ldaw r0, sp[254]
+; CHECK-NEXT: bl f5
+; CHECK-NEXT: retsp 257
+define void @f8() nounwind {
+entry:
+  %0 = alloca [256 x i32]
+  %1 = getelementptr inbounds [256 x i32]* %0, i32 0, i32 253
+  call void @f5(i32* %1)
+  ret void
+}
 
 ; FP + large frame: spill FP+SR+LR = entsp 2 + 32768  + extsp 1
-; CHECKFP-LABEL:f8
+; CHECKFP-LABEL:f9
 ; CHECKFP: entsp 32770
 ; CHECKFP-NEXT: stw r10, sp[1]
 ; CHECKFP-NEXT: ldaw r10, sp[0]
-; CHECKFP-NEXT: mkmsk r1, 15
-; CHECKFP-NEXT: ldaw r0, r10[r1]
+; CHECKFP-NEXT: ldc [[REG:r[0-9]+]], 32767
+; CHECKFP-NEXT: ldaw r0, r10{{\[}}[[REG]]{{\]}}
 ; CHECKFP-NEXT: extsp 1
 ; CHECKFP-NEXT: bl f5
 ; CHECKFP-NEXT: ldaw sp, sp[1]
 ; CHECKFP-NEXT: set sp, r10
 ; CHECKFP-NEXT: ldw r10, sp[1]
 ; CHECKFP-NEXT: retsp 32770
 ;
 ; !FP + large frame: spill SR+SR+LR = entsp 3 + 32768
-; CHECK-LABEL:f8
+; CHECK-LABEL:f9
 ; CHECK: entsp 32771
 ; CHECK-NEXT: ldaw r0, sp[32768]
 ; CHECK-NEXT: bl f5
 ; CHECK-NEXT: retsp 32771
-define void @f8() nounwind {
+define void @f9() nounwind {
 entry:
   %0 = alloca [32768 x i32]
   %1 = getelementptr inbounds [32768 x i32]* %0, i32 0, i32 32765
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