generalize this code so that fast isel handles integer truncates to i1, which
codegen to the same thing as integer truncates to i8 (the top bits are
just undefined). This implements rdar://6667338
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66902 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index 61ca24e..d6cdc3f 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -1002,7 +1002,9 @@
return false;
MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType());
MVT DstVT = TLI.getValueType(I->getType());
- if (DstVT != MVT::i8)
+
+ // This code only handles truncation to byte right now.
+ if (DstVT != MVT::i8 && DstVT != MVT::i1)
// All other cases should be handled by the tblgen generated code.
return false;
if (SrcVT != MVT::i16 && SrcVT != MVT::i32)
@@ -1022,7 +1024,7 @@
BuildMI(MBB, DL, TII.get(CopyOpc), CopyReg).addReg(InputReg);
// Then issue an extract_subreg.
- unsigned ResultReg = FastEmitInst_extractsubreg(DstVT.getSimpleVT(),
+ unsigned ResultReg = FastEmitInst_extractsubreg(MVT::i8,
CopyReg, X86::SUBREG_8BIT);
if (!ResultReg)
return false;