[AArch64InstPrinter] prefer bfi to bfc for < armv8.2-a

Summary:
Fixes pr/42576.

Link: https://github.com/ClangBuiltLinux/linux/issues/697

Reviewers: t.p.northover

Reviewed By: t.p.northover

Subscribers: kristof.beyls, hiraditya, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68356

llvm-svn: 373655

4 files changed, 24 insertions, 9 deletions

diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64InstPrinter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64InstPrinter.cpp
index d0a544273b8..1a16468484a 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64InstPrinter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64InstPrinter.cpp
@@ -172,7 +172,8 @@ void AArch64InstPrinter::printInst(const MCInst *MI, raw_ostream &O,
     int ImmS = MI->getOperand(4).getImm();
 
     if ((Op2.getReg() == AArch64::WZR || Op2.getReg() == AArch64::XZR) &&
-        (ImmR == 0 || ImmS < ImmR)) {
+        (ImmR == 0 || ImmS < ImmR) &&
+        STI.getFeatureBits()[AArch64::HasV8_2aOps]) {
       // BFC takes precedence over its entire range, sligtly differently to BFI.
       int BitWidth = Opcode == AArch64::BFMXri ? 64 : 32;
       int LSB = (BitWidth - ImmR) % BitWidth;
diff --git a/llvm/test/MC/AArch64/armv8.2a-bfc.s b/llvm/test/MC/AArch64/armv8.2a-bfc.s
new file mode 100644
index 00000000000..1346850d401
--- /dev/null
+++ b/llvm/test/MC/AArch64/armv8.2a-bfc.s
@@ -0,0 +1,11 @@
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s | FileCheck %s --check-prefix=BFI
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=+v8.1a | FileCheck %s --check-prefix=BFI
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=-v8.2a | FileCheck %s --check-prefix=BFI
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=+v8.2a | FileCheck %s --check-prefix=BFC
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=+v8.3a | FileCheck %s --check-prefix=BFC
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=+v8.4a | FileCheck %s --check-prefix=BFC
+// RUN: llvm-mc -triple aarch64-linux-gnu -o - %s -mattr=+v8.5a | FileCheck %s --check-prefix=BFC
+  bfc w0, #1, #5
+
+// BFI: bfi w0, wzr, #1, #5
+// BFC: bfc w0, #1, #5
diff --git a/llvm/test/MC/AArch64/basic-a64-instructions.s b/llvm/test/MC/AArch64/basic-a64-instructions.s
index 07afdba8c37..0cb8e3eb207 100644
--- a/llvm/test/MC/AArch64/basic-a64-instructions.s
+++ b/llvm/test/MC/AArch64/basic-a64-instructions.s
@@ -978,7 +978,7 @@ _func:
         bfm x5, x6, #12, #63
 // CHECK: bfi      x4, x5, #52, #11           // encoding: [0xa4,0x28,0x4c,0xb3]
 // CHECK: bfxil    xzr, x4, #0, #1            // encoding: [0x9f,0x00,0x40,0xb3]
-// CHECK: bfc      x4, #1, #6                 // encoding: [0xe4,0x17,0x7f,0xb3]
+// CHECK: bfi      x4, xzr, #1, #6            // encoding: [0xe4,0x17,0x7f,0xb3]
 // CHECK: bfxil    x5, x6, #12, #52           // encoding: [0xc5,0xfc,0x4c,0xb3]
 
         sxtb w1, w2
@@ -1078,7 +1078,7 @@ _func:
 // CHECK: bfxil    w9, w10, #0, #32           // encoding: [0x49,0x7d,0x00,0x33]
 // CHECK: bfi      w11, w12, #31, #1          // encoding: [0x8b,0x01,0x01,0x33]
 // CHECK: bfi      w13, w14, #29, #3          // encoding: [0xcd,0x09,0x03,0x33]
-// CHECK: bfc      xzr, #10, #11              // encoding: [0xff,0x2b,0x76,0xb3]
+// CHECK: bfi      xzr, xzr, #10, #11         // encoding: [0xff,0x2b,0x76,0xb3]
 
         bfxil w9, w10, #0, #1
         bfxil x2, x3, #63, #1
@@ -1137,10 +1137,10 @@ _func:
         bfc wzr, #31, #1
         bfc x0, #5, #9
         bfc xzr, #63, #1
-// CHECK: bfc w3, #0, #32             // encoding: [0xe3,0x7f,0x00,0x33]
-// CHECK: bfc wzr, #31, #1            // encoding: [0xff,0x03,0x01,0x33]
-// CHECK: bfc x0, #5, #9              // encoding: [0xe0,0x23,0x7b,0xb3]
-// CHECK: bfc xzr, #63, #1            // encoding: [0xff,0x03,0x41,0xb3]
+// CHECK: bfxil w3, wzr, #0, #32      // encoding: [0xe3,0x7f,0x00,0x33]
+// CHECK: bfi wzr, wzr, #31, #1       // encoding: [0xff,0x03,0x01,0x33]
+// CHECK: bfi x0, xzr, #5, #9         // encoding: [0xe0,0x23,0x7b,0xb3]
+// CHECK: bfi xzr, xzr, #63, #1       // encoding: [0xff,0x03,0x41,0xb3]
 
 //------------------------------------------------------------------------------
 // Compare & branch (immediate)
diff --git a/llvm/test/MC/Disassembler/AArch64/basic-a64-instructions.txt b/llvm/test/MC/Disassembler/AArch64/basic-a64-instructions.txt
index 74edc4c4a54..482dd1f68ed 100644
--- a/llvm/test/MC/Disassembler/AArch64/basic-a64-instructions.txt
+++ b/llvm/test/MC/Disassembler/AArch64/basic-a64-instructions.txt
@@ -1,6 +1,7 @@
 # RUN: llvm-mc -triple=aarch64 -mattr=+fp-armv8 -disassemble < %s | FileCheck %s
 # RUN: llvm-mc -triple=arm64 -mattr=+fp-armv8 -disassemble < %s | FileCheck %s
 # RUN: llvm-mc -triple=arm64 -mattr=+fp-armv8,+fullfp16 -disassemble < %s | FileCheck %s --check-prefix=CHECK --check-prefix=FP16
+# RUN: llvm-mc -triple=arm64 -mattr=+v8.2a -disassemble < %s | FileCheck %s --check-prefix=CHECK-V82
 # RUN: llvm-mc -triple=arm64 -mattr=+v8.3a -disassemble < %s | FileCheck %s --check-prefix=CHECK-V83
 
 #------------------------------------------------------------------------------
@@ -624,7 +625,8 @@
 
 # CHECK: bfi      x4, x5, #52, #11
 # CHECK: bfxil    xzr, x4, #0, #1
-# CHECK: bfc      x4, #1, #6
+# CHECK: bfi      x4, xzr, #1, #6
+# CHECK-V82: bfc      x4, #1, #6
 # CHECK: bfxil    x5, x6, #12, #52
 0xa4 0x28 0x4c 0xb3
 0x9f 0x0 0x40 0xb3
@@ -717,7 +719,8 @@
 # CHECK: bfxil    w9, w10, #0, #32
 # CHECK: bfi      w11, w12, #31, #1
 # CHECK: bfi      w13, w14, #29, #3
-# CHECK: bfc      xzr, #10, #11
+# CHECK-V82: bfc      xzr, #10, #11
+# CHECK: bfi      xzr, xzr, #10, #11
 0x49 0x1 0x0 0x33
 0x62 0x0 0x41 0xb3
 0x93 0xfe 0x40 0xb3