[ARM] GlobalISel: Support frem for 32-bit values

Legalize to a libcall.
On this occasion, also start allowing soft float subtargets. For the
moment G_FREM is the only legal floating point operation for them.

llvm-svn: 299753

lib/Target/ARM/ARMCallLowering.cpp

@@ -333,10 +333,6 @@ bool ARMCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
   if (Subtarget->isThumb())
     return false;
 
-  // FIXME: Support soft float (when we're ready to generate libcalls)
-  if (Subtarget->useSoftFloat() || !Subtarget->hasVFP2())
-    return false;
-
   for (auto &Arg : F.args())
     if (!isSupportedType(DL, TLI, Arg.getType()))
       return false;

lib/Target/ARM/ARMLegalizerInfo.cpp

@@ -57,7 +57,7 @@ ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
 
   setAction({G_CONSTANT, s32}, Legal);
 
-  if (ST.hasVFP2()) {
+  if (!ST.useSoftFloat() && ST.hasVFP2()) {
     setAction({G_FADD, s32}, Legal);
     setAction({G_FADD, s64}, Legal);
 
@@ -65,5 +65,7 @@ ARMLegalizerInfo::ARMLegalizerInfo(const ARMSubtarget &ST) {
     setAction({G_STORE, s64}, Legal);
   }
 
+  setAction({G_FREM, s32}, Libcall);
+
   computeTables();
 }

test/CodeGen/ARM/GlobalISel/arm-isel-fp.ll

@@ -0,0 +1,11 @@
+; RUN: llc -mtriple arm-unknown -mattr=+vfp2 -float-abi=hard -global-isel %s -o - | FileCheck %s
+; RUN: llc -mtriple arm-unknown -mattr=+vfp2 -float-abi=soft -global-isel %s -o - | FileCheck %s
+; RUN: llc -mtriple arm-unknwon -float-abi=soft -global-isel %s -o - | FileCheck %s
+
+define arm_aapcscc float @test_frem_float(float %x, float %y) {
+; CHECK-LABEL: test_frem_float:
+; CHECK: blx fmodf
+  %r = frem float %x, %y
+  ret float %r
+}
+

test/CodeGen/ARM/GlobalISel/arm-legalize-fp.mir

@@ -0,0 +1,37 @@
+# RUN: llc -mtriple arm-- -mattr=+vfp2 -float-abi=hard -global-isel -run-pass=legalizer %s -o - | FileCheck %s
+# RUN: llc -mtriple arm-- -mattr=+vfp2 -float-abi=soft -global-isel -run-pass=legalizer %s -o - | FileCheck %s
+# RUN: llc -mtriple arm-- -float-abi=soft -global-isel -run-pass=legalizer %s -o - | FileCheck %s
+--- |
+  define void @test_frem_float() { ret void }
+...
+---
+name:            test_frem_float
+# CHECK-LABEL: name: test_frem_float
+legalized:       false
+# CHECK: legalized: true
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _ }
+  - { id: 1, class: _ }
+  - { id: 2, class: _ }
+body:             |
+  bb.0:
+    liveins: %r0, %r1
+
+    ; CHECK-DAG: [[X:%[0-9]+]](s32) = COPY %r0
+    ; CHECK-DAG: [[Y:%[0-9]+]](s32) = COPY %r1
+    %0(s32) = COPY %r0
+    %1(s32) = COPY %r1
+    ; CHECK: ADJCALLSTACKDOWN
+    ; CHECK-DAG: %r0 = COPY [[X]]
+    ; CHECK-DAG: %r1 = COPY [[Y]]
+    ; CHECK: BLX $fmodf, {{.*}}, implicit %r0, implicit %r1, implicit-def %r0
+    ; CHECK: [[R:%[0-9]+]](s32) = COPY %r0
+    ; CHECK: ADJCALLSTACKUP
+    %2(s32) = G_FREM %0, %1
+    ; CHECK: %r0 = COPY [[R]]
+    %r0 = COPY %2(s32)
+    BX_RET 14, _, implicit %r0
+...