[Mips] Add rematerialization support for ldi.fmt

Instruction ldi.fmt can be considered cheap enough to avoid spill and restore
of value that it produces since it's loaded from immediate.

Differential Revision: https://reviews.llvm.org/D69898

2 files changed, 108 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsMSAInstrInfo.td b/llvm/lib/Target/Mips/MipsMSAInstrInfo.td
index f585d9c1a14..0fef518c240 100644
--- a/llvm/lib/Target/Mips/MipsMSAInstrInfo.td
+++ b/llvm/lib/Target/Mips/MipsMSAInstrInfo.td
@@ -1287,6 +1287,7 @@ class MSA_I10_LDI_DESC_BASE<string instr_asm, RegisterOperand ROWD,
   // LDI is matched using custom matching code in MipsSEISelDAGToDAG.cpp
   list<dag> Pattern = [];
   bit hasSideEffects = 0;
+  bit isReMaterializable = 1;
   InstrItinClass Itinerary = itin;
 }
 
diff --git a/llvm/test/CodeGen/Mips/msa/remat-ldi.ll b/llvm/test/CodeGen/Mips/msa/remat-ldi.ll
new file mode 100644
index 00000000000..64f976c97a3
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/msa/remat-ldi.ll
@@ -0,0 +1,107 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -O3 -march=mipsel -mcpu=mips32r6 -mattr=+fp64,+msa %s -o - | FileCheck %s
+
+; Test that checks if spill for ldi can be avoided and instruction will be
+; rematerialized.
+
+declare dso_local void @foo()
+
+define dso_local void @test_ldi_b() {
+; CHECK-LABEL: test_ldi_b:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addiu $sp, $sp, -24
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    sw $ra, 20($sp) # 4-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset 31, -4
+; CHECK-NEXT:    ldi.b $w0, 1
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    jal foo
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    ldi.b $w0, 1
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    lw $ra, 20($sp) # 4-byte Folded Reload
+; CHECK-NEXT:    jr $ra
+; CHECK-NEXT:    addiu $sp, $sp, 24
+entry:
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<16 x i8> <i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1>)
+  tail call void @foo()
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<16 x i8> <i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1>)
+  ret void
+}
+
+define dso_local void @test_ldi_h() {
+; CHECK-LABEL: test_ldi_h:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addiu $sp, $sp, -24
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    sw $ra, 20($sp) # 4-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset 31, -4
+; CHECK-NEXT:    ldi.h $w0, 2
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    jal foo
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    ldi.h $w0, 2
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    lw $ra, 20($sp) # 4-byte Folded Reload
+; CHECK-NEXT:    jr $ra
+; CHECK-NEXT:    addiu $sp, $sp, 24
+entry:
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<8 x i16> <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>)
+  tail call void @foo()
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<8 x i16> <i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>)
+  ret void
+}
+
+define dso_local void @test_ldi_w() {
+; CHECK-LABEL: test_ldi_w:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addiu $sp, $sp, -24
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    sw $ra, 20($sp) # 4-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset 31, -4
+; CHECK-NEXT:    ldi.w $w0, 3
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    jal foo
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    ldi.w $w0, 3
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    lw $ra, 20($sp) # 4-byte Folded Reload
+; CHECK-NEXT:    jr $ra
+; CHECK-NEXT:    addiu $sp, $sp, 24
+entry:
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<4 x i32> <i32 3, i32 3, i32 3, i32 3>)
+  tail call void @foo()
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<4 x i32> <i32 3, i32 3, i32 3, i32 3>)
+  ret void
+}
+
+define dso_local void @test_ldi_d() {
+; CHECK-LABEL: test_ldi_d:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addiu $sp, $sp, -24
+; CHECK-NEXT:    .cfi_def_cfa_offset 24
+; CHECK-NEXT:    sw $ra, 20($sp) # 4-byte Folded Spill
+; CHECK-NEXT:    .cfi_offset 31, -4
+; CHECK-NEXT:    ldi.d $w0, 4
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    jal foo
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    ldi.d $w0, 4
+; CHECK-NEXT:    #APP
+; CHECK-NEXT:    #NO_APP
+; CHECK-NEXT:    lw $ra, 20($sp) # 4-byte Folded Reload
+; CHECK-NEXT:    jr $ra
+; CHECK-NEXT:    addiu $sp, $sp, 24
+entry:
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<2 x i64> <i64 4, i64 4>)
+  tail call void @foo()
+  tail call void asm sideeffect "", "f,~{memory},~{$1}"(<2 x i64> <i64 4, i64 4>)
+  ret void
+}