[mono] respect hardfloat/softloat setting in ARM ABI (#16)

lewurm · luhenry · commit c97510286a58 · 2018-11-07T17:10:31.000-05:00
Mono's LLVM backend was always emitting code like this: > 000d7234 <double_ToString>: > d7234: e92d4800 push {fp, lr} > d7238: ed2d8b02 vpush {d8} > d723c: ed908b00 vldr d8, [r0] > d7240: eb12e4e2 bl 5905d0 <plt_System_Globalization_NumberFormatInfo_get_CurrentInfo> > d7244: e1a03000 mov r3, r0 > d7248: ec510b18 vmov r0, r1, d8 > d724c: e3a02000 mov r2, #0 > d7250: eb12e91a bl 5916c0 <plt_System_Number_FormatDouble_double_string_System_Globalization_NumberFormatInfo> > d7254: ecbd8b02 vpop {d8} > d7258: e8bd8800 pop {fp, pc} despite the correct setting passed to `llc`. Note that passing the floating point value (`d8`) in the integer registers `r0` and `r1` is wrong. With this change we get the following: > 000d9934 <double_ToString>: > d9934: e92d4800 push {fp, lr} > d9938: ed2d8b02 vpush {d8} > d993c: ed908b00 vldr d8, [r0] > d9940: eb137c2e bl 5b8a00 <plt_System_Globalization_NumberFormatInfo_get_CurrentInfo> > d9944: eeb00b48 vmov.f64 d0, d8 > d9948: e1a01000 mov r1, r0 > d994c: e3a00000 mov r0, #0 > d9950: eb138066 bl 5b9af0 <plt_System_Number_FormatDouble_double_string_System_Globalization_NumberFormatInfo> > d9954: ecbd8b02 vpop {d8} > d9958: e8bd4800 pop {fp, lr} > d995c: e1a0f00e mov pc, lr Which matches with what the Mono JIT emits: > 0: e92d4100 push {r8, lr} > 4: e24dd028 sub sp, sp, #40 ; 0x28 > 8: e58d0018 str r0, [sp, #24] > c: e59d0018 ldr r0, [sp, #24] > 10: ed900b00 vldr d0, [r0] > 14: ed8d0b08 vstr d0, [sp, #32] > 18: eb00000e bl 0x58 > 1c: e1a01000 mov r1, r0 > 20: ed9d0b08 vldr d0, [sp, #32] > 24: e3a00000 mov r0, #0 > 28: eb000007 bl 0x4c > 2c: e28dd028 add sp, sp, #40 ; 0x28 > 30: e8bd8100 pop {r8, pc} Both are passing the floating point argument correctly via `d0`. Fixes mono/mono#11095
diff --git a/lib/Target/ARM/ARMCallingConv.td b/lib/Target/ARM/ARMCallingConv.td
@@ -334,3 +334,11 @@ def CC_ARM_Mono_AAPCS : CallingConv<[
   CCDelegateTo<CC_ARM_AAPCS>
 ]>;
 
+def CC_ARM_Mono_AAPCS_VFP : CallingConv<[
+  // Mono marks the parameter it wants to pass in this non-abi register with
+  // the 'inreg' attribute.
+  CCIfInReg<CCAssignToReg<[R8]>>,
+
+  CCDelegateTo<CC_ARM_AAPCS_VFP>
+]>;
+
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1623,10 +1623,13 @@ CCAssignFn *ARMTargetLowering::CCAssignFnForNode(CallingConv::ID CC,
     if (Return) {
       return CCAssignFnForNode(CallingConv::C, true, isVarArg);
     } else {
-      if (Subtarget->isAAPCS_ABI())
-        return CC_ARM_Mono_AAPCS;
-      else
-        return CC_ARM_Mono_APCS;
+      if (Subtarget->isAAPCS_ABI()) {
+          if (Subtarget->hasVFP2() && !Subtarget->isThumb1Only() && !isVarArg)
+              return CC_ARM_Mono_AAPCS_VFP;
+          else
+              return CC_ARM_Mono_AAPCS;
+      } else
+          return CC_ARM_Mono_APCS;
     }
   }
 }

Original file line number	Diff line number	Diff line change
`@@ -1623,10 +1623,13 @@ CCAssignFn *ARMTargetLowering::CCAssignFnForNode(CallingConv::ID CC,`
`1623`	`1623`	`if (Return) {`
`1624`	`1624`	`return CCAssignFnForNode(CallingConv::C, true, isVarArg);`
`1625`	`1625`	`} else {`
`1626`		`- if (Subtarget->isAAPCS_ABI())`
`1627`		`- return CC_ARM_Mono_AAPCS;`
`1628`		`- else`
`1629`		`- return CC_ARM_Mono_APCS;`
	`1626`	`+ if (Subtarget->isAAPCS_ABI()) {`
	`1627`	`+ if (Subtarget->hasVFP2() && !Subtarget->isThumb1Only() && !isVarArg)`
	`1628`	`+ return CC_ARM_Mono_AAPCS_VFP;`
	`1629`	`+ else`
	`1630`	`+ return CC_ARM_Mono_AAPCS;`
	`1631`	`+ } else`
	`1632`	`+ return CC_ARM_Mono_APCS;`
`1630`	`1633`	`}`
`1631`	`1634`	`}`
`1632`	`1635`	`}`