Since LI/LIS sign extend the constant passed into the instruction we should

check that the sign extended constant fits into 16-bits if we want a
zero extended value, otherwise go ahead and put it together piecemeal.

Fixes PR26356.

llvm-svn: 259177

2 files changed, 12 insertions, 2 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCFastISel.cpp b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
index 81682ddd235..41f5f3928ef 100644
--- a/llvm/lib/Target/PowerPC/PPCFastISel.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
@@ -2098,7 +2098,9 @@ unsigned PPCFastISel::PPCMaterializeInt(const ConstantInt *CI, MVT VT,
     BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), ImmReg)
         .addImm(CI->getSExtValue());
     return ImmReg;
-  } else if (!UseSExt && isUInt<16>(CI->getZExtValue())) {
+  } else if (!UseSExt && isUInt<16>(CI->getSExtValue())) {
+    // Since LI will sign extend the constant we need to make sure that for
+    // our zeroext constants that the sign extended constant fits into 16-bits.
     unsigned Opc = (VT == MVT::i64) ? PPC::LI8 : PPC::LI;
     unsigned ImmReg = createResultReg(RC);
     BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), ImmReg)
@@ -2108,7 +2110,6 @@ unsigned PPCFastISel::PPCMaterializeInt(const ConstantInt *CI, MVT VT,
 
   // Construct the constant piecewise.
   int64_t Imm = CI->getZExtValue();
-
   if (VT == MVT::i64)
     return PPCMaterialize64BitInt(Imm, RC);
   else if (VT == MVT::i32)
diff --git a/llvm/test/CodeGen/PowerPC/fast-isel-ret.ll b/llvm/test/CodeGen/PowerPC/fast-isel-ret.ll
index e05ef7d9ab8..0adb5a93510 100644
--- a/llvm/test/CodeGen/PowerPC/fast-isel-ret.ll
+++ b/llvm/test/CodeGen/PowerPC/fast-isel-ret.ll
@@ -186,3 +186,12 @@ entry:
 ; ELF64: blr
   ret i32 -1
 }
+
+define zeroext i16 @ret20() nounwind {
+entry:
+; ELF64-LABEL: ret20
+; ELF64: lis{{.*}}0
+; ELF64: ori{{.*}}32768
+; ELF64: blr
+  ret i16 32768
+}