[X86][regcall] Support passing / returning structures

Currently, the regcall calling conversion in Clang doesn't match with
ICC when passing / returning structures. https://godbolt.org/z/axxKMKrW7

This patch tries to fix the problem to match with ICC.

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D122104

1 files changed, 19 insertions, 10 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 6cfc3c5..e2ffd57 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -833,6 +833,7 @@ CGFunctionInfo *CGFunctionInfo::create(unsigned llvmCC,
   FI->NumArgs = argTypes.size();
   FI->HasExtParameterInfos = !paramInfos.empty();
   FI->getArgsBuffer()[0].type = resultType;
+  FI->MaxVectorWidth = 0;
   for (unsigned i = 0, e = argTypes.size(); i != e; ++i)
     FI->getArgsBuffer()[i + 1].type = argTypes[i];
   for (unsigned i = 0, e = paramInfos.size(); i != e; ++i)
@@ -4668,6 +4669,19 @@ public:
 
 } // namespace
 
+static unsigned getMaxVectorWidth(const llvm::Type *Ty) {
+  if (auto *VT = dyn_cast<llvm::VectorType>(Ty))
+    return VT->getPrimitiveSizeInBits().getKnownMinSize();
+  if (auto *AT = dyn_cast<llvm::ArrayType>(Ty))
+    return getMaxVectorWidth(AT->getElementType());
+
+  unsigned MaxVectorWidth = 0;
+  if (auto *ST = dyn_cast<llvm::StructType>(Ty))
+    for (auto *I : ST->elements())
+      MaxVectorWidth = std::max(MaxVectorWidth, getMaxVectorWidth(I));
+  return MaxVectorWidth;
+}
+
 RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
                                  const CGCallee &Callee,
                                  ReturnValueSlot ReturnValue,
@@ -5221,12 +5235,9 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
 #endif
 
   // Update the largest vector width if any arguments have vector types.
-  for (unsigned i = 0; i < IRCallArgs.size(); ++i) {
-    if (auto *VT = dyn_cast<llvm::VectorType>(IRCallArgs[i]->getType()))
-      LargestVectorWidth =
-          std::max((uint64_t)LargestVectorWidth,
-                   VT->getPrimitiveSizeInBits().getKnownMinSize());
-  }
+  for (unsigned i = 0; i < IRCallArgs.size(); ++i)
+    LargestVectorWidth = std::max(LargestVectorWidth,
+                                  getMaxVectorWidth(IRCallArgs[i]->getType()));
 
   // Compute the calling convention and attributes.
   unsigned CallingConv;
@@ -5348,10 +5359,8 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
     CI->setName("call");
 
   // Update largest vector width from the return type.
-  if (auto *VT = dyn_cast<llvm::VectorType>(CI->getType()))
-    LargestVectorWidth =
-        std::max((uint64_t)LargestVectorWidth,
-                 VT->getPrimitiveSizeInBits().getKnownMinSize());
+  LargestVectorWidth =
+      std::max(LargestVectorWidth, getMaxVectorWidth(CI->getType()));
 
   // Insert instrumentation or attach profile metadata at indirect call sites.
   // For more details, see the comment before the definition of