[CodeGen] Update min-legal-vector width based on function argument and return types

This is a continuation of my patches to inform the X86 backend about what the largest IR types are in the function so that we can restrict the backend type legalizer to prevent 512-bit vectors on SKX when -mprefer-vector-width=256 is specified if no explicit 512 bit vectors were specified by the user.

This patch updates the vector width based on the argument and return types of the current function and from the types of any functions it calls. This is intended to make sure the backend type legalizer doesn't disturb any types that are required for ABI.

Differential Revision: https://reviews.llvm.org/D52441

llvm-svn: 345168

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 7b181a01c82..cf6aec0ff24 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -4240,6 +4240,13 @@ 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(LargestVectorWidth,
+                                    VT->getPrimitiveSizeInBits());
+  }
+
   // Compute the calling convention and attributes.
   unsigned CallingConv;
   llvm::AttributeList Attrs;
@@ -4320,6 +4327,11 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   if (!CI->getType()->isVoidTy())
     CI->setName("call");
 
+  // Update largest vector width from the return type.
+  if (auto *VT = dyn_cast<llvm::VectorType>(CI->getType()))
+    LargestVectorWidth = std::max(LargestVectorWidth,
+                                  VT->getPrimitiveSizeInBits());
+
   // Insert instrumentation or attach profile metadata at indirect call sites.
   // For more details, see the comment before the definition of
   // IPVK_IndirectCallTarget in InstrProfData.inc.