[X86] Lower zext i1 arguments

i1 is now a legal type for X86 with AVX512.
There were some paths in X86FastISel which were not quite ready to see
an i1 value: they were not quite sure how to deal with sign/zero extends
for call arguments.
DTRT by extending to i8 for zeroext and bailing out of FastISel for
signext.

This fixes PR27591.

llvm-svn: 268470

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index 6eab3f1d6af..d3894525996 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -3019,6 +3019,10 @@ bool X86FastISel::fastLowerCall(CallLoweringInfo &CLI) {
     case CCValAssign::SExt: {
       assert(VA.getLocVT().isInteger() && !VA.getLocVT().isVector() &&
              "Unexpected extend");
+
+      if (ArgVT.SimpleTy == MVT::i1)
+        return false;
+
       bool Emitted = X86FastEmitExtend(ISD::SIGN_EXTEND, VA.getLocVT(), ArgReg,
                                        ArgVT, ArgReg);
       assert(Emitted && "Failed to emit a sext!"); (void)Emitted;
@@ -3028,6 +3032,17 @@ bool X86FastISel::fastLowerCall(CallLoweringInfo &CLI) {
     case CCValAssign::ZExt: {
       assert(VA.getLocVT().isInteger() && !VA.getLocVT().isVector() &&
              "Unexpected extend");
+
+      // Handle zero-extension from i1 to i8, which is common.
+      if (ArgVT.SimpleTy == MVT::i1) {
+        // Set the high bits to zero.
+        ArgReg = fastEmitZExtFromI1(MVT::i8, ArgReg, /*TODO: Kill=*/false);
+        ArgVT = MVT::i8;
+
+        if (ArgReg == 0)
+          return false;
+      }
+
       bool Emitted = X86FastEmitExtend(ISD::ZERO_EXTEND, VA.getLocVT(), ArgReg,
                                        ArgVT, ArgReg);
       assert(Emitted && "Failed to emit a zext!"); (void)Emitted;