[PATCH] D60704: [ARM] Disallow SP and PC in VMOVRH and VMOVHR.

[Simon Tatham via Phabricator via llvm-commits]

simon_tatham created this revision.
simon_tatham added reviewers: dmgreen, samparker, SjoerdMeijer.
Herald added subscribers: llvm-commits, hiraditya, kristof.beyls, javed.absar.
Herald added a project: LLVM.

Arm v8.1-M supports the VMOV instructions that move a half-precision
value to and from a GPR, but not if the GPR is SP or PC.

This change affects the same instructions in other architectures as
well. Strictly speaking, that's not quite right (in Arm v8-A, it's not
UNPREDICTABLE to move a half precision value into SP), but it seems
unlikely that those instructions are particularly useful.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D60704

Files:
  llvm/lib/Target/ARM/ARMInstrVFP.td


Index: llvm/lib/Target/ARM/ARMInstrVFP.td
===================================================================
--- llvm/lib/Target/ARM/ARMInstrVFP.td
+++ llvm/lib/Target/ARM/ARMInstrVFP.td
@@ -1246,9 +1246,9 @@
 
 // Move H->R, clearing top 16 bits
 def VMOVRH : AVConv2I<0b11100001, 0b1001,
-                      (outs GPR:$Rt), (ins HPR:$Sn),
+                      (outs rGPR:$Rt), (ins HPR:$Sn),
                       IIC_fpMOVSI, "vmov", ".f16\t$Rt, $Sn",
-                      [(set GPR:$Rt, (arm_vmovrh HPR:$Sn))]>,
+                      [(set rGPR:$Rt, (arm_vmovrh HPR:$Sn))]>,
              Requires<[HasFPRegs16]>,
              Sched<[WriteFPMOV]> {
   // Instruction operands.
@@ -1268,9 +1268,9 @@
 
 // Move R->H, clearing top 16 bits
 def VMOVHR : AVConv4I<0b11100000, 0b1001,
-                      (outs HPR:$Sn), (ins GPR:$Rt),
+                      (outs HPR:$Sn), (ins rGPR:$Rt),
                       IIC_fpMOVIS, "vmov", ".f16\t$Sn, $Rt",
-                      [(set HPR:$Sn, (arm_vmovhr GPR:$Rt))]>,
+                      [(set HPR:$Sn, (arm_vmovhr rGPR:$Rt))]>,
              Requires<[HasFPRegs16]>,
              Sched<[WriteFPMOV]> {
   // Instruction operands.


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