[mips] Honour -mno-odd-spreg for vector insert/extract when MSA is enabled.

Summary:
-mno-odd-spreg prohibits the use of odd-numbered single-precision floating
point registers. However, vector insert/extract was still using them when
manipulating the subregisters of an MSA register. Fixed this by ensuring
that insertion/extraction is only performed on even-numbered vector
registers when -mno-odd-spreg is given.

Reviewers: vmedic, sstankovic

Reviewed By: sstankovic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7672

llvm-svn: 230235

lib/Target/Mips/MipsRegisterInfo.td

@@ -398,6 +398,8 @@ def MSA128W: RegisterClass<"Mips", [v4i32, v4f32], 128,
                            (sequence "W%u", 0, 31)>;
 def MSA128D: RegisterClass<"Mips", [v2i64, v2f64], 128,
                            (sequence "W%u", 0, 31)>;
+def MSA128WEvens: RegisterClass<"Mips", [v4i32, v4f32], 128,
+                                (decimate (sequence "W%u", 0, 31), 2)>;
 
 def MSACtrl: RegisterClass<"Mips", [i32], 32, (add
   MSAIR, MSACSR, MSAAccess, MSASave, MSAModify, MSARequest, MSAMap, MSAUnmap)>;

lib/Target/Mips/MipsSEISelLowering.cpp

@@ -2878,10 +2878,21 @@ emitCOPY_FW(MachineInstr *MI, MachineBasicBlock *BB) const{
   unsigned Ws = MI->getOperand(1).getReg();
   unsigned Lane = MI->getOperand(2).getImm();
 
-  if (Lane == 0)
+  if (Lane == 0) {
-    BuildMI(*BB, MI, DL, TII->get(Mips::COPY), Fd).addReg(Ws, 0, Mips::sub_lo);
+    unsigned Wt = Ws;
-  else {
+    if (!Subtarget.useOddSPReg()) {
-    unsigned Wt = RegInfo.createVirtualRegister(&Mips::MSA128WRegClass);
+      // We must copy to an even-numbered MSA register so that the
+      // single-precision sub-register is also guaranteed to be even-numbered.
+      Wt = RegInfo.createVirtualRegister(&Mips::MSA128WEvensRegClass);
+
+      BuildMI(*BB, MI, DL, TII->get(Mips::COPY), Wt).addReg(Ws);
+    }
+
+    BuildMI(*BB, MI, DL, TII->get(Mips::COPY), Fd).addReg(Wt, 0, Mips::sub_lo);
+  } else {
+    unsigned Wt = RegInfo.createVirtualRegister(
+        Subtarget.useOddSPReg() ? &Mips::MSA128WRegClass :
+                                  &Mips::MSA128WEvensRegClass);
 
     BuildMI(*BB, MI, DL, TII->get(Mips::SPLATI_W), Wt).addReg(Ws).addImm(Lane);
     BuildMI(*BB, MI, DL, TII->get(Mips::COPY), Fd).addReg(Wt, 0, Mips::sub_lo);
@@ -2941,7 +2952,9 @@ MipsSETargetLowering::emitINSERT_FW(MachineInstr *MI,
   unsigned Wd_in = MI->getOperand(1).getReg();
   unsigned Lane = MI->getOperand(2).getImm();
   unsigned Fs = MI->getOperand(3).getReg();
-  unsigned Wt = RegInfo.createVirtualRegister(&Mips::MSA128WRegClass);
+  unsigned Wt = RegInfo.createVirtualRegister(
+      Subtarget.useOddSPReg() ? &Mips::MSA128WRegClass :
+                                &Mips::MSA128WEvensRegClass);
 
   BuildMI(*BB, MI, DL, TII->get(Mips::SUBREG_TO_REG), Wt)
       .addImm(0)

test/CodeGen/Mips/no-odd-spreg-msa.ll

@@ -0,0 +1,131 @@
+; RUN: llc -march=mipsel -mcpu=mips32 -mattr=+fp64,+msa,-nooddspreg < %s | FileCheck %s -check-prefix=ALL -check-prefix=ODDSPREG
+; RUN: llc -march=mipsel -mcpu=mips32 -mattr=+fp64,+msa,+nooddspreg < %s | FileCheck %s -check-prefix=ALL -check-prefix=NOODDSPREG
+
+@v4f32 = global <4 x float> zeroinitializer
+
+define void @msa_insert_0(float %a) {
+entry:
+  ; Force the float into an odd-numbered register using named registers and
+  ; load the vector.
+  %b = call float asm sideeffect "mov.s $0, $1", "={$f13},{$f12}" (float %a)
+  %0 = load volatile <4 x float>* @v4f32
+
+  ; Clobber all except $f12/$w12 and $f13
+  ;
+  ; The intention is that if odd single precision registers are permitted, the
+  ; allocator will choose $f12/$w12 for the vector and $f13 for the float to
+  ; avoid the spill/reload.
+  ;
+  ; On the other hand, if odd single precision registers are not permitted, it
+  ; must copy $f13 to an even-numbered register before inserting into the
+  ; vector.
+  call void asm sideeffect "# Clobber", "~{$f0},~{$f1},~{$f2},~{$f3},~{$f4},~{$f5},~{$f6},~{$f7},~{$f8},~{$f9},~{$f10},~{$f11},~{$f14},~{$f15},~{$f16},~{$f17},~{$f18},~{$f19},~{$f20},~{$f21},~{$f22},~{$f23},~{$f24},~{$f25},~{$f26},~{$f27},~{$f28},~{$f29},~{$f30},~{$f31}"()
+  %1 = insertelement <4 x float> %0, float %b, i32 0
+  store <4 x float> %1, <4 x float>* @v4f32
+  ret void
+}
+
+; ALL-LABEL:  msa_insert_0:
+; ALL:            mov.s $f13, $f12
+; ALL:            lw $[[R0:[0-9]+]], %got(v4f32)(
+; ALL:            ld.w $w[[W0:[0-9]+]], 0($[[R0]])
+; NOODDSPREG:     mov.s $f[[F0:[0-9]+]], $f13
+; NOODDSPREG:     insve.w $w[[W0]][0], $w[[F0]][0]
+; ODDSPREG:       insve.w $w[[W0]][0], $w13[0]
+; ALL:            # Clobber
+; ALL-NOT: sdc1
+; ALL-NOT: ldc1
+; ALL:            st.w $w[[W0]], 0($[[R0]])
+
+define void @msa_insert_1(float %a) {
+entry:
+  ; Force the float into an odd-numbered register using named registers and
+  ; load the vector.
+  %b = call float asm sideeffect "mov.s $0, $1", "={$f13},{$f12}" (float %a)
+  %0 = load volatile <4 x float>* @v4f32
+
+  ; Clobber all except $f12/$w12 and $f13
+  ;
+  ; The intention is that if odd single precision registers are permitted, the
+  ; allocator will choose $f12/$w12 for the vector and $f13 for the float to
+  ; avoid the spill/reload.
+  ;
+  ; On the other hand, if odd single precision registers are not permitted, it
+  ; must copy $f13 to an even-numbered register before inserting into the
+  ; vector.
+  call void asm sideeffect "# Clobber", "~{$f0},~{$f1},~{$f2},~{$f3},~{$f4},~{$f5},~{$f6},~{$f7},~{$f8},~{$f9},~{$f10},~{$f11},~{$f14},~{$f15},~{$f16},~{$f17},~{$f18},~{$f19},~{$f20},~{$f21},~{$f22},~{$f23},~{$f24},~{$f25},~{$f26},~{$f27},~{$f28},~{$f29},~{$f30},~{$f31}"()
+  %1 = insertelement <4 x float> %0, float %b, i32 1
+  store <4 x float> %1, <4 x float>* @v4f32
+  ret void
+}
+
+; ALL-LABEL:  msa_insert_1:
+; ALL:            mov.s $f13, $f12
+; ALL:            lw $[[R0:[0-9]+]], %got(v4f32)(
+; ALL:            ld.w $w[[W0:[0-9]+]], 0($[[R0]])
+; NOODDSPREG:     mov.s $f[[F0:[0-9]+]], $f13
+; NOODDSPREG:     insve.w $w[[W0]][1], $w[[F0]][0]
+; ODDSPREG:       insve.w $w[[W0]][1], $w13[0]
+; ALL:            # Clobber
+; ALL-NOT: sdc1
+; ALL-NOT: ldc1
+; ALL:            st.w $w[[W0]], 0($[[R0]])
+
+define float @msa_extract_0() {
+entry:
+  %0 = load volatile <4 x float>* @v4f32
+  %1 = call <4 x float> asm sideeffect "move.v $0, $1", "={$w13},{$w12}" (<4 x float> %0)
+
+  ; Clobber all except $f12, and $f13
+  ;
+  ; The intention is that if odd single precision registers are permitted, the
+  ; allocator will choose $f13/$w13 for the vector since that saves on moves.
+  ;
+  ; On the other hand, if odd single precision registers are not permitted, it
+  ; must move it to $f12/$w12.
+  call void asm sideeffect "# Clobber", "~{$f0},~{$f1},~{$f2},~{$f3},~{$f4},~{$f5},~{$f6},~{$f7},~{$f8},~{$f9},~{$f10},~{$f11},~{$f14},~{$f15},~{$f16},~{$f17},~{$f18},~{$f19},~{$f20},~{$f21},~{$f22},~{$f23},~{$f24},~{$f25},~{$f26},~{$f27},~{$f28},~{$f29},~{$f30},~{$f31}"()
+
+  %2 = extractelement <4 x float> %1, i32 0
+  ret float %2
+}
+
+; ALL-LABEL:  msa_extract_0:
+; ALL:            lw $[[R0:[0-9]+]], %got(v4f32)(
+; ALL:            ld.w $w12, 0($[[R0]])
+; ALL:            move.v $w[[W0:13]], $w12
+; NOODDSPREG:     move.v $w[[W0:12]], $w13
+; ALL:            # Clobber
+; ALL-NOT: st.w
+; ALL-NOT: ld.w
+; ALL:            mov.s $f0, $f[[W0]]
+
+define float @msa_extract_1() {
+entry:
+  %0 = load volatile <4 x float>* @v4f32
+  %1 = call <4 x float> asm sideeffect "move.v $0, $1", "={$w13},{$w12}" (<4 x float> %0)
+
+  ; Clobber all except $f13
+  ;
+  ; The intention is that if odd single precision registers are permitted, the
+  ; allocator will choose $f13/$w13 for the vector since that saves on moves.
+  ;
+  ; On the other hand, if odd single precision registers are not permitted, it
+  ; must be spilled.
+  call void asm sideeffect "# Clobber", "~{$f0},~{$f1},~{$f2},~{$f3},~{$f4},~{$f5},~{$f6},~{$f7},~{$f8},~{$f9},~{$f10},~{$f11},~{$f12},~{$f14},~{$f15},~{$f16},~{$f17},~{$f18},~{$f19},~{$f20},~{$f21},~{$f22},~{$f23},~{$f24},~{$f25},~{$f26},~{$f27},~{$f28},~{$f29},~{$f30},~{$f31}"()
+
+  %2 = extractelement <4 x float> %1, i32 1
+  ret float %2
+}
+
+; ALL-LABEL:  msa_extract_1:
+; ALL:            lw $[[R0:[0-9]+]], %got(v4f32)(
+; ALL:            ld.w $w12, 0($[[R0]])
+; ALL:            splati.w $w[[W0:[0-9]+]], $w13[1]
+; NOODDSPREG:     st.w $w[[W0]], 0($sp)
+; ODDSPREG-NOT: st.w
+; ODDSPREG-NOT: ld.w
+; ALL:            # Clobber
+; ODDSPREG-NOT: st.w
+; ODDSPREG-NOT: ld.w
+; NOODDSPREG:     ld.w $w0, 0($sp)
+; ODDSPREG:       mov.s $f0, $f[[W0]]