[ARM] Reject CSEL instructions with invalid operands

Summary:
According to the Armv8.1-M manual CSEL, CSINC, CSINV and CSNEG are
"constrained unpredictable" when SP is used as the source register Rn.

The assembler should diagnose this case.

Reviewers: momchil.velikov, dmgreen, ostannard, simon_tatham, t.p.northover

Reviewed By: ostannard

Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65505

llvm-svn: 367433

3 files changed, 31 insertions, 14 deletions

diff --git a/llvm/lib/Target/ARM/ARMInstrThumb2.td b/llvm/lib/Target/ARM/ARMInstrThumb2.td
index b9691efa3e1..7e74a0a3845 100644
--- a/llvm/lib/Target/ARM/ARMInstrThumb2.td
+++ b/llvm/lib/Target/ARM/ARMInstrThumb2.td
@@ -5235,7 +5235,7 @@ def t2LoopEnd :
 } // end isNotDuplicable
 
 class CS<string iname, bits<4> opcode, list<dag> pattern=[]>
-  : V8_1MI<(outs rGPR:$Rd), (ins GPRwithZR:$Rn, GPRwithZRnosp:$Rm, pred_noal:$fcond),
+  : V8_1MI<(outs rGPR:$Rd), (ins GPRwithZRnosp:$Rn, GPRwithZRnosp:$Rm, pred_noal:$fcond),
            AddrModeNone, NoItinerary, iname, "$Rd, $Rn, $Rm, $fcond", "", pattern> {
   bits<4> Rd;
   bits<4> Rm;
diff --git a/llvm/test/MC/ARM/thumbv8.1m.s b/llvm/test/MC/ARM/thumbv8.1m.s
index b24f998a1f0..f4f30566642 100644
--- a/llvm/test/MC/ARM/thumbv8.1m.s
+++ b/llvm/test/MC/ARM/thumbv8.1m.s
@@ -1117,6 +1117,24 @@ csinv   lr, r2, r2, mi
 # CHECK-NOLOB: csel r0, r0, r1, eq @ encoding: [0x50,0xea,0x01,0x80]
 csel r0, r0, r1, eq
 
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14
+csel sp, r0, r1, eq
+
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14 or zr
+csel r0, sp, r1, eq
+
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14 or zr
+csinc r0, sp, r1, eq
+
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14 or zr
+csinv r0, sp, r1, eq
+
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14 or zr
+csneg r0, sp, r1, eq
+
+// ERROR: :[[@LINE+1]]:{{[0-9]+}}: error: operand must be a register in range [r0, r12] or r14 or zr
+csel r0, r0, sp, eq
+
 // ERROR: :[[@LINE+2]]:{{[0-9]+}}: error: instructions in IT block must be predicable
 it eq
 csel r0, r0, r1, eq
diff --git a/llvm/test/MC/Disassembler/ARM/thumbv8.1m.s b/llvm/test/MC/Disassembler/ARM/thumbv8.1m.s
index 68dcbd23a04..845c50ef9e6 100644
--- a/llvm/test/MC/Disassembler/ARM/thumbv8.1m.s
+++ b/llvm/test/MC/Disassembler/ARM/thumbv8.1m.s
@@ -42,8 +42,7 @@
 # ERROR: [[@LINE-2]]:2: warning: potentially undefined instruction encoding
 
 [0x5d,0xea,0x02,0x80]
-# CHECK: csel r0, sp, r2, eq @ encoding: [0x5d,0xea,0x02,0x80]
-# ERROR: [[@LINE-2]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x51,0xea,0x0d,0x80]
 # ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
@@ -52,37 +51,37 @@
 # ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x22 0x9e]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x47 0x9e]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x3c 0xae]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x3a 0xbe]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x7b 0x89]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x1f 0x9e]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x3f 0xae]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0xd7 0x9e]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x2f 0xae]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x42 0xae]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x5d 0xea 0x7b 0xbe]
-# ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding
+# ERROR: [[@LINE-1]]:2: warning: invalid instruction encoding
 
 [0x52 0xea 0x22 0x9d]
 # ERROR: [[@LINE-1]]:2: warning: potentially undefined instruction encoding