[PATCH] [Mips] Return false for isFPCloseToIncomingSP()

[Vladimir Radosavljevic]

Hi petarj, dsanders,

On Mips, frame pointer points to the same side of the frame as the stack pointer.
This function is used to decide where to put register scavenging spill slot. So far, it was put on the wrong side of the frame, and was to far away from $fp if frame is larger than 2^15 bytes.

REPOSITORY
  rL LLVM

http://reviews.llvm.org/D8895

Files:
  lib/Target/Mips/MipsFrameLowering.h
  test/CodeGen/Mips/vector-multiply.ll

Index: lib/Target/Mips/MipsFrameLowering.h
===================================================================
--- lib/Target/Mips/MipsFrameLowering.h
+++ lib/Target/Mips/MipsFrameLowering.h
@@ -32,6 +32,8 @@
 
   bool hasFP(const MachineFunction &MF) const override;
 
+  bool isFPCloseToIncomingSP() const override { return false; }
+
   void
   eliminateCallFramePseudoInstr(MachineFunction &MF,
                                 MachineBasicBlock &MBB,
Index: test/CodeGen/Mips/vector-multiply.ll
===================================================================
--- /dev/null
+++ test/CodeGen/Mips/vector-multiply.ll
@@ -0,0 +1,28 @@
+; RUN: llc -march=mipsel -O0 < %s
+
+define i32 @main(i32 signext %argc, i8** %argv) "no-frame-pointer-elim"="true" {
+entry:
+  %retval = alloca i32, align 4
+  %argc.addr = alloca i32, align 4
+  %argv.addr = alloca i8**, align 4
+  %v0 = alloca <16 x i8>, align 16
+  %.compoundliteral = alloca <16 x i8>, align 16
+  %v1 = alloca <16 x i8>, align 16
+  %.compoundliteral1 = alloca <16 x i8>, align 16
+  %unused_variable = alloca [16384 x i32], align 4
+  %result = alloca <16 x i8>, align 16
+  store i32 0, i32* %retval
+  store i32 %argc, i32* %argc.addr, align 4
+  store i8** %argv, i8*** %argv.addr, align 4
+  store <16 x i8> <i8 1, i8 2, i8 3, i8 4, i8 5, i8 6, i8 7, i8 8, i8 9, i8 10, i8 11, i8 12, i8 13, i8 14, i8 15, i8 16>, <16 x i8>* %.compoundliteral
+  %0 = load <16 x i8>, <16 x i8>* %.compoundliteral
+  store <16 x i8> %0, <16 x i8>* %v0, align 16
+  store <16 x i8> zeroinitializer, <16 x i8>* %.compoundliteral1
+  %1 = load <16 x i8>, <16 x i8>* %.compoundliteral1
+  store <16 x i8> %1, <16 x i8>* %v1, align 16
+  %2 = load <16 x i8>, <16 x i8>* %v0, align 16
+  %3 = load <16 x i8>, <16 x i8>* %v1, align 16
+  %mul = mul <16 x i8> %2, %3
+  store <16 x i8> %mul, <16 x i8>* %result, align 16
+  ret i32 0
+}

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