[mips] Impose a threshold for coercion of aggregates

Modified MipsABIInfo::classifyArgumentType so that it now coerces aggregate
structures only if the size of said aggregate is less than 16/64 bytes,
depending on the ABI.

Patch by Stefan Maksimovic.

Differential Revision: https://reviews.llvm.org/D32900

llvm-svn: 302547

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 4ebbef7dfb5..5d3ccb86ff8 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -6695,6 +6695,14 @@ MipsABIInfo::classifyArgumentType(QualType Ty, uint64_t &Offset) const {
       return getNaturalAlignIndirect(Ty, RAA == CGCXXABI::RAA_DirectInMemory);
     }
 
+    // Use indirect if the aggregate cannot fit into registers for
+    // passing arguments according to the ABI
+    unsigned Threshold = IsO32 ? 16 : 64;
+
+    if(getContext().getTypeSizeInChars(Ty) > CharUnits::fromQuantity(Threshold))
+      return ABIArgInfo::getIndirect(CharUnits::fromQuantity(Align), true,
+                                     getContext().getTypeAlign(Ty) / 8 > Align);
+
     // If we have reached here, aggregates are passed directly by coercing to
     // another structure type. Padding is inserted if the offset of the
     // aggregate is unaligned.