[mips] Teach the delay slot filler to transform 'jal' for microMIPS

ISel is currently picking 'JAL' over 'JAL_MM' for calling a function when
targeting microMIPS. A later patch will correct this behaviour.

This patch extends the mechanism for transforming instructions into their short
delay to recognise 'JAL_MM' for transforming into 'JALS_MM'.

llvm-svn: 330825

2 files changed, 71 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
index b12c7e7760a..4f292e66ce0 100644
--- a/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
+++ b/llvm/lib/Target/Mips/MipsDelaySlotFiller.cpp
@@ -575,6 +575,7 @@ static int getEquivalentCallShort(int Opcode) {
   case Mips::BLTZAL:
     return Mips::BLTZALS_MM;
   case Mips::JAL:
+  case Mips::JAL_MM:
     return Mips::JALS_MM;
   case Mips::JALR:
     return Mips::JALRS_MM;
diff --git a/llvm/test/CodeGen/Mips/micromips-short-delay-slot.mir b/llvm/test/CodeGen/Mips/micromips-short-delay-slot.mir
new file mode 100644
index 00000000000..89f20a5d906
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/micromips-short-delay-slot.mir
@@ -0,0 +1,70 @@
+# RUN: llc -march=mips -mcpu=mips32r2 -mattr=+micromips %s -o - \
+# RUN:     -start-after=block-placement | FileCheck %s
+
+# Test that the micromips jal instruction is correctly handled by the delay slot
+# filler by converting it to a short delay slot for the li instruction.
+
+# CHECK-LABEL: caller13
+# CHECK:      jals callee13
+# CHECK-NEXT: li16
+
+--- |
+  declare i32 @callee13(i32, i32)
+
+  define i32 @caller13() {
+  entry:
+    %call = tail call i32 (i32, i32) @callee13(i32 1, i32 2)
+    ret i32 %call
+  }
+
+...
+---
+name:            caller13
+alignment:       2
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+registers:
+liveins:
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       24
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    true
+  hasCalls:        true
+  stackProtector:  ''
+  maxCallFrameSize: 16
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:
+stack:
+  - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+      stack-id: 0, callee-saved-register: '$ra', callee-saved-restored: true,
+      di-variable: '', di-expression: '', di-location: '' }
+constants:
+body:             |
+  bb.0.entry:
+    liveins: $ra
+
+    $sp = ADDiu $sp, -24
+    CFI_INSTRUCTION def_cfa_offset 24
+    SW killed $ra, $sp, 20 :: (store 4 into %stack.0)
+    CFI_INSTRUCTION offset $ra_64, -4
+    $a0 = LI16_MM 1
+    $a1 = LI16_MM 2
+    JAL_MM @callee13, csr_o32, implicit-def dead $ra, implicit killed $a0, implicit killed $a1, implicit-def $sp, implicit-def $v0
+    $ra = LW $sp, 20 :: (load 4 from %stack.0)
+    $sp = ADDiu $sp, 24
+    PseudoReturn undef $ra, implicit $v0
+
+
+...