[PATCH] D24465: [ARM] Support ldr.w in pseudo instruction ldr rd, =immediate

[Peter Smith via llvm-commits]

peter.smith created this revision.
peter.smith added reviewers: rengolin, t.p.northover, jmolloy.
peter.smith added a subscriber: llvm-commits.
Herald added subscribers: samparker, rengolin, aemerson.

The changes to allow ldr rd, =immediate to be transformed into a MOV 
http://reviews.llvm.org/D20153
http://reviews.llvm.org/D20154
http://reviews.llvm.org/D20155
caused a regression from LLVM 3.8 as they have no support for the ldr.w rd, =immediate form in Thumb 2 whereas 3.8 did. In ARM the .w is silently ignored by the parser so this problem is restricted to Thumb2.

This patch adds support for ldr.w rd, =immediate for Thumb 2. I've followed the form of the t2LDRpcrel family and added a t2InstAlias for the .w form. This will cause the parser to add an extra operand ".w" that the ARMAsmParser.cpp code has to account for.

Fixes PR30352

https://reviews.llvm.org/D24465

Files:
  lib/Target/ARM/ARMInstrThumb2.td
  lib/Target/ARM/AsmParser/ARMAsmParser.cpp
  test/MC/ARM/ldr-pseudo-wide.s

Index: test/MC/ARM/ldr-pseudo-wide.s
===================================================================
--- test/MC/ARM/ldr-pseudo-wide.s
+++ test/MC/ARM/ldr-pseudo-wide.s
@@ -0,0 +1,56 @@
+@ Test case for PR30352
+@ Check that ldr.w is:
+@ accepted and ignored for ARM
+@ accepted and propagated for Thumb2
+@ rejected as needing Thumb2 for Thumb
+
+ at RUN llvm-mc -triple armv5-unknown-linux-gnueabi %s | FileCheck --check-prefix=CHECK-ARM --check-prefix=CHECK %s
+ at RUN: llvm-mc -triple   armv7-base-apple-darwin %s | FileCheck --check-prefix=CHECK-DARWIN-ARM --check-prefix=CHECK %s
+ at RUN: llvm-mc -triple thumbv7-unknown-linux-gnueabi %s | FileCheck --check-prefix=CHECK-THUMB2 --check-prefix=CHECK %s
+ at RUN: llvm-mc -triple thumbv7-base-apple-darwin %s | FileCheck --check-prefix=CHECK-DARWIN-THUMB2 --check-prefix=CHECK %s
+ at RUN: not llvm-mc -triple thumbv6-unknown-linux-gnueabi %s 2>&1 | FileCheck --check-prefix=CHECK-THUMB %s
+ at RUN: not llvm-mc -triple thumbv6-base-apple-darwin %s 2>&1 | FileCheck --check-prefix=CHECK-THUMB %s
+@ CHECK-LABEL: f1:
+f1:
+  ldr r0, =0x10002
+@ CHECK-ARM: ldr r0, .Ltmp[[TMP0:[0-9]+]]
+@ CHECK-DARWIN-ARM: ldr r0, Ltmp0
+@ CHECK-THUMB2: ldr r0, .Ltmp[[TMP0:[0-9]+]]
+@ CHECK-DARWIN-THUMB2: ldr r0, Ltmp0
+
+  ldr.w r0, =0x10002
+@ CHECK-ARM: ldr r0, .Ltmp[[TMP1:[0-9]+]]
+@ CHECK-DARWIN-ARM: ldr r0, Ltmp1
+@ CHECK-THUMB2: ldr.w r0, .Ltmp[[TMP1:[0-9]+]]
+@ CHECK-DARWIN-THUMB2: ldr.w r0, Ltmp1
+@ CHECK-THUMB: error: instruction requires: thumb2
+@ CHECK-THUMB-NEXT:  ldr.w r0, =0x10002
+@ CHECK-THUMB-NEXT:  ^
+
+@ CHECK-LABEL: f2:
+f2:
+  ldr r0, =foo
+@ CHECK-ARM: ldr r0, .Ltmp[[TMP2:[0-9]+]]
+@ CHECK-DARWIN-ARM: ldr r0, Ltmp2
+@ CHECK-THUMB2: ldr r0, .Ltmp[[TMP2:[0-9]+]]
+@ CHECK-DARWIN-THUMB2: ldr r0, Ltmp2
+
+  ldr.w r0, =foo
+@ CHECK-ARM: ldr r0, .Ltmp[[TMP3:[0-9]+]]
+@ CHECK-DARWIN-ARM: ldr r0, Ltmp3
+@ CHECK-THUMB2: ldr.w r0, .Ltmp[[TMP3:[0-9]+]]
+@ CHECK-DARWIN-THUMB2: ldr.w r0, Ltmp3
+@ CHECK-THUMB: error: instruction requires: thumb2
+@ CHECK-THUMB-NEXT:  ldr.w r0, =foo
+@ CHECK-THUMB-NEXT:  ^
+
+@ CHECK-LABEL: f3:
+f3:
+  ldr.w r1, =0x1
+@ CHECK-ARM: mov r1, #1
+@ CHECK-DARWIN-ARM: mov r1, #1
+@ CHECK-THUMB2: mov.w r1, #1
+@ CHECK-DARWIN-THUMB2: mov.w r1, #1
+@ CHECK-THUMB: error: instruction requires: thumb2
+@ CHECK-THUMB-NEXT:  ldr.w r1, =0x1
+@ CHECK-THUMB-NEXT:  ^
Index: lib/Target/ARM/AsmParser/ARMAsmParser.cpp
===================================================================
--- lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -7103,6 +7103,9 @@
     else if (Inst.getOpcode() == ARM::t2LDRConstPool)
       TmpInst.setOpcode(ARM::t2LDRpci);
     const ARMOperand &PoolOperand =
+      (static_cast<ARMOperand &>(*Operands[2]).isToken() &&
+       static_cast<ARMOperand &>(*Operands[2]).getToken() == ".w") ?
+      static_cast<ARMOperand &>(*Operands[4]) :
       static_cast<ARMOperand &>(*Operands[3]);
     const MCExpr *SubExprVal = PoolOperand.getConstantPoolImm();
     // If SubExprVal is a constant we may be able to use a MOV
Index: lib/Target/ARM/ARMInstrThumb2.td
===================================================================
--- lib/Target/ARM/ARMInstrThumb2.td
+++ lib/Target/ARM/ARMInstrThumb2.td
@@ -4657,6 +4657,10 @@
 def t2LDRConstPool
   : t2AsmPseudo<"ldr${p} $Rt, $immediate",
                 (ins GPRnopc:$Rt, const_pool_asm_imm:$immediate, pred:$p)>;
+// Version w/ the .w suffix.
+def : t2InstAlias<"ldr${p}.w $Rt, $immediate",
+                  (t2LDRConstPool GPRnopc:$Rt,
+                  const_pool_asm_imm:$immediate, pred:$p)>;
 
 // PLD/PLDW/PLI with alternate literal form.
 def : t2InstAlias<"pld${p} $addr",


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