[AArch64][GISel] and+or+shl => bfi

This fixes a GISEL vs SDAG regression that showed up at -Os in 256.bzip2

In `_getAndMoveToFrontDecode`:

gisel:
```
and w9, w0, #0xff
orr w9, w9, w8, lsl #8
```

sdag:
```
bfi w0, w8, #8, #24
```

Differential revision: https://reviews.llvm.org/D103291

Author: jroelofs

llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp

@@ -2163,6 +2163,40 @@ bool AArch64InstructionSelector::earlySelect(MachineInstr &I) {
     I.eraseFromParent();
     return true;
   }
+  case TargetOpcode::G_OR: {
+    // Look for operations that take the lower `Width=Size-ShiftImm` bits of
+    // `ShiftSrc` and insert them into the upper `Width` bits of `MaskSrc` via
+    // shifting and masking that we can replace with a BFI (encoded as a BFM).
+    Register Dst = I.getOperand(0).getReg();
+    LLT Ty = MRI.getType(Dst);
+
+    if (!Ty.isScalar())
+      return false;
+
+    unsigned Size = Ty.getSizeInBits();
+    if (Size != 32 && Size != 64)
+      return false;
+
+    Register ShiftSrc;
+    int64_t ShiftImm;
+    Register MaskSrc;
+    int64_t MaskImm;
+    if (!mi_match(
+            Dst, MRI,
+            m_GOr(m_OneNonDBGUse(m_GShl(m_Reg(ShiftSrc), m_ICst(ShiftImm))),
+                  m_OneNonDBGUse(m_GAnd(m_Reg(MaskSrc), m_ICst(MaskImm))))))
+      return false;
+
+    if (ShiftImm > Size || ((1ULL << ShiftImm) - 1ULL) != uint64_t(MaskImm))
+      return false;
+
+    int64_t Immr = Size - ShiftImm;
+    int64_t Imms = Size - ShiftImm - 1;
+    unsigned Opc = Size == 32 ? AArch64::BFMWri : AArch64::BFMXri;
+    emitInstr(Opc, {Dst}, {MaskSrc, ShiftSrc, Immr, Imms}, MIB);
+    I.eraseFromParent();
+    return true;
+  }
   default:
     return false;
   }

llvm/test/CodeGen/AArch64/GlobalISel/select-bitfield-insert.ll

@@ -0,0 +1,157 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -o - -verify-machineinstrs -global-isel=1 -global-isel-abort=1 | FileCheck %s --check-prefixes=CHECK,GISEL
+; RUN: llc < %s -o - -verify-machineinstrs -global-isel=0 | FileCheck %s --check-prefixes=CHECK,SDAG
+
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-apple-ios14.5.0"
+
+define i32 @bfi_w_31(i32 %in1, i32 %in2) {
+; CHECK-LABEL: bfi_w_31:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi w1, w0, #31, #1
+; CHECK-NEXT:    mov w0, w1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i32 %in1, 31
+  %tmp4 = and i32 %in2, 2147483647
+  %out = or i32 %tmp3, %tmp4
+  ret i32 %out
+}
+
+define i32 @bfi_w_8(i32 %in1, i32 %in2) {
+; CHECK-LABEL: bfi_w_8:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi w1, w0, #8, #24
+; CHECK-NEXT:    mov w0, w1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i32 %in1, 8
+  %tmp4 = and i32 %in2, 255
+  %out = or i32 %tmp3, %tmp4
+  ret i32 %out
+}
+
+define i32 @bfi_w_1(i32 %in1, i32 %in2) {
+; CHECK-LABEL: bfi_w_1:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi w1, w0, #1, #31
+; CHECK-NEXT:    mov w0, w1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i32 %in1, 1
+  %tmp4 = and i32 %in2, 1
+  %out = or i32 %tmp3, %tmp4
+  ret i32 %out
+}
+
+define i64 @bfi_x_63(i64 %in1, i64 %in2) {
+; CHECK-LABEL: bfi_x_63:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi x1, x0, #63, #1
+; CHECK-NEXT:    mov x0, x1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 63
+  %tmp4 = and i64 %in2, 9223372036854775807
+  %out = or i64 %tmp3, %tmp4
+  ret i64 %out
+}
+
+define i64 @bfi_x_31(i64 %in1, i64 %in2) {
+; CHECK-LABEL: bfi_x_31:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi x1, x0, #31, #33
+; CHECK-NEXT:    mov x0, x1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 31
+  %tmp4 = and i64 %in2, 2147483647
+  %out = or i64 %tmp3, %tmp4
+  ret i64 %out
+}
+
+define i64 @bfi_x_8(i64 %in1, i64 %in2) {
+; CHECK-LABEL: bfi_x_8:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi x1, x0, #8, #56
+; CHECK-NEXT:    mov x0, x1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 8
+  %tmp4 = and i64 %in2, 255
+  %out = or i64 %tmp3, %tmp4
+  ret i64 %out
+}
+
+define i64 @bfi_x_1(i64 %in1, i64 %in2) {
+; CHECK-LABEL: bfi_x_1:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi x1, x0, #1, #63
+; CHECK-NEXT:    mov x0, x1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 1
+  %tmp4 = and i64 %in2, 1
+  %out = or i64 %tmp3, %tmp4
+  ret i64 %out
+}
+
+define i64 @bfi_x_1_swapped(i64 %in1, i64 %in2) {
+; CHECK-LABEL: bfi_x_1_swapped:
+; CHECK:       ; %bb.0: ; %bb
+; CHECK-NEXT:    bfi x1, x0, #1, #63
+; CHECK-NEXT:    mov x0, x1
+; CHECK-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 1
+  %tmp4 = and i64 %in2, 1
+  %out = or i64 %tmp4, %tmp3
+  ret i64 %out
+}
+
+define i64 @extra_use1(i64 %in1, i64 %in2, i64* %p) {
+; GISEL-LABEL: extra_use1:
+; GISEL:       ; %bb.0: ; %bb
+; GISEL-NEXT:    lsl x8, x0, #1
+; GISEL-NEXT:    and x9, x1, #0x1
+; GISEL-NEXT:    orr x0, x8, x9
+; GISEL-NEXT:    str x8, [x2]
+; GISEL-NEXT:    ret
+;
+; SDAG-LABEL: extra_use1:
+; SDAG:       ; %bb.0: ; %bb
+; SDAG-NEXT:    bfi x1, x0, #1, #63
+; SDAG-NEXT:    lsl x8, x0, #1
+; SDAG-NEXT:    mov x0, x1
+; SDAG-NEXT:    str x8, [x2]
+; SDAG-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 1
+  %tmp4 = and i64 %in2, 1
+  %out = or i64 %tmp3, %tmp4
+  store i64 %tmp3, i64* %p
+  ret i64 %out
+}
+
+define i64 @extra_use2(i64 %in1, i64 %in2, i64* %p) {
+; GISEL-LABEL: extra_use2:
+; GISEL:       ; %bb.0: ; %bb
+; GISEL-NEXT:    and x8, x1, #0x1
+; GISEL-NEXT:    orr x0, x8, x0, lsl #1
+; GISEL-NEXT:    str x8, [x2]
+; GISEL-NEXT:    ret
+;
+; SDAG-LABEL: extra_use2:
+; SDAG:       ; %bb.0: ; %bb
+; SDAG-NEXT:    and x8, x1, #0x1
+; SDAG-NEXT:    bfi x1, x0, #1, #63
+; SDAG-NEXT:    mov x0, x1
+; SDAG-NEXT:    str x8, [x2]
+; SDAG-NEXT:    ret
+bb:
+  %tmp3 = shl i64 %in1, 1
+  %tmp4 = and i64 %in2, 1
+  %out = or i64 %tmp3, %tmp4
+  store i64 %tmp4, i64* %p
+  ret i64 %out
+}