ARM IAS: support emitting constant values in target expressions

A 32-bit immediate value can be formed from a constant expression and loaded
into a register.  Add support to emit this into an object file.  Because this
value is a constant, a relocation must *not* be produced for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199023 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 25a3d4df43556ad07b893b98d001addb4357bab6..4c0098f8e9d9bff1ae446274411d2ae119f47531 100644 (file)
--- a/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -26,6 +26,7 @@
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCRegisterInfo.h"
 #include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -912,6 +913,20 @@ ARMMCCodeEmitter::getHiLo16ImmOpValue(const MCInst &MI, unsigned OpIdx,
     const ARMMCExpr *ARM16Expr = cast<ARMMCExpr>(E);
     E = ARM16Expr->getSubExpr();
 
+    if (const MCConstantExpr *MCE = dyn_cast<MCConstantExpr>(E)) {
+      const int64_t Value = MCE->getValue();
+      if (Value > UINT32_MAX)
+        report_fatal_error("constant value truncated (limited to 32-bit)");
+
+      switch (ARM16Expr->getKind()) {
+      case ARMMCExpr::VK_ARM_HI16:
+        return (int32_t(Value) & 0xffff0000) >> 16;
+      case ARMMCExpr::VK_ARM_LO16:
+        return (int32_t(Value) & 0x0000ffff);
+      default: llvm_unreachable("Unsupported ARMFixup");
+      }
+    }
+
     switch (ARM16Expr->getKind()) {
     default: llvm_unreachable("Unsupported ARMFixup");
     case ARMMCExpr::VK_ARM_HI16:

diff --git a/test/MC/ARM/target-expressions.s b/test/MC/ARM/target-expressions.s
index 350408c07938f8fb40ff17630694b2496005058d..c87cd22b2bad1b740ac23358e0a506cb251b63ea 100644 (file)
--- a/test/MC/ARM/target-expressions.s
+++ b/test/MC/ARM/target-expressions.s
@@ -1,4 +1,6 @@
 @ RUN: llvm-mc -triple armv7-eabi -filetype asm -o - %s | FileCheck %s
+@ RUN: llvm-mc -triple armv7-eabi -filetype obj -o - %s | llvm-readobj -r \
+@ RUN:   | FileCheck -check-prefix CHECK-RELOCATIONS %s
 
        .syntax unified
 
@@ -6,6 +8,9 @@
 function:
        bx lr
 
+       .global external
+       .type external,%function
+
 .set deadbeat, 0xdeadbea7
 
        .type test,%function
@@ -28,6 +33,18 @@ test:
        movw r5, #:lower16:0xD1510D6E
        movt r5, #:upper16:0xD1510D6E
 
+       movw r0, :lower16:external
+       movt r0, :upper16:external
+
+       movw r1, #:lower16:external
+       movt r1, #:upper16:external
+
+       movw r2, #:lower16:(16 + 16)
+       movt r2, #:upper16:(16 + 16)
+
+       movw r3, :lower16:(16 + 16)
+       movt r3, :upper16:(16 + 16)
+
 @ CHECK-LABEL: test:
 @ CHECK:       movw r0, :lower16:function
 @ CHECK:       movt r0, :upper16:function
@@ -41,4 +58,23 @@ test:
 @ CHECK:       movt r4, :upper16:(3511749998)
 @ CHECK:       movw r5, :lower16:(3511749998)
 @ CHECK:       movt r5, :upper16:(3511749998)
+@ CHECK:       movw r0, :lower16:external
+@ CHECK:       movt r0, :upper16:external
+@ CHECK:       movw r1, :lower16:external
+@ CHECK:       movt r1, :upper16:external
+@ CHECK:       movw r2, :lower16:(32)
+@ CHECK:       movt r2, :upper16:(32)
+@ CHECK:       movw r3, :lower16:(32)
+@ CHECK:       movt r3, :upper16:(32)
+
+@ CHECK-RELOCATIONS: Relocations [
+@ CHECK-RELOCATIONS:   0x4 R_ARM_MOVW_ABS_NC function 0x0
+@ CHECK-RELOCATIONS:   0x8 R_ARM_MOVT_ABS function 0x0
+@ CHECK-RELOCATIONS:   0xC R_ARM_MOVW_ABS_NC function 0x0
+@ CHECK-RELOCATIONS:   0x10 R_ARM_MOVT_ABS function 0x0
+@ CHECK-RELOCATIONS:   0x34 R_ARM_MOVW_ABS_NC external 0x0
+@ CHECK-RELOCATIONS:   0x38 R_ARM_MOVT_ABS external 0x0
+@ CHECK-RELOCATIONS:   0x3C R_ARM_MOVW_ABS_NC external 0x0
+@ CHECK-RELOCATIONS:   0x40 R_ARM_MOVT_ABS external 0x0
+@ CHECK-RELOCATIONS: ]