[mips] Fix microMIPS unconditional branch offset handling

MipsSEInstrInfo class defines for internal purpose unconditional
branches as Mips::B nad Mips:J even in case of microMIPS code
generation. Under some conditions that leads to the bug - for rather long
branch which fits to Mips jump instruction offset size, but does not fit
to microMIPS jump offset size, we generate 'short' branch and later show
an error 'out of range PC16 fixup' after check in the isBranchOffsetInRange
routine.

Differential revision: https://reviews.llvm.org/D50615

llvm-svn: 340932

2 files changed, 105 insertions, 2 deletions

diff --git a/llvm/lib/Target/Mips/MipsSEInstrInfo.cpp b/llvm/lib/Target/Mips/MipsSEInstrInfo.cpp
index 9f697cd03cb..e8589fc5349 100644
--- a/llvm/lib/Target/Mips/MipsSEInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsSEInstrInfo.cpp
@@ -25,9 +25,14 @@
 
 using namespace llvm;
 
+static unsigned getUnconditionalBranch(const MipsSubtarget &STI) {
+  if (STI.inMicroMipsMode())
+    return STI.isPositionIndependent() ? Mips::B_MM : Mips::J_MM;
+  return STI.isPositionIndependent() ? Mips::B : Mips::J;
+}
+
 MipsSEInstrInfo::MipsSEInstrInfo(const MipsSubtarget &STI)
-    : MipsInstrInfo(STI, STI.isPositionIndependent() ? Mips::B : Mips::J),
-      RI() {}
+    : MipsInstrInfo(STI, getUnconditionalBranch(STI)), RI() {}
 
 const MipsRegisterInfo &MipsSEInstrInfo::getRegisterInfo() const {
   return RI;
diff --git a/llvm/test/CodeGen/Mips/micromips-b-range.ll b/llvm/test/CodeGen/Mips/micromips-b-range.ll
new file mode 100644
index 00000000000..f761d1c31d3
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/micromips-b-range.ll
@@ -0,0 +1,98 @@
+; RUN: llc -march=mips -relocation-model=pic -mattr=+micromips \
+; RUN:     -filetype=obj -o - %s | llvm-objdump -d - | FileCheck %s
+
+; CHECK-LABEL: foo:
+; CHECK-NEXT:     0:	41 a2 00 00 	lui	$2, 0
+; CHECK-NEXT:     4:	30 42 00 00 	addiu	$2, $2, 0
+; CHECK-NEXT:     8:	03 22 11 50 	addu	$2, $2, $25
+; CHECK-NEXT:     c:	fc 42 00 00 	lw	$2, 0($2)
+; CHECK-NEXT:    10:	69 20 	      lw16	$2, 0($2)
+; CHECK-NEXT:    12:	40 c2 00 14 	bgtz	$2, 44 <foo+0x3e>
+; CHECK-NEXT:    16:	00 00 00 00 	nop
+; CHECK-NEXT:    1a:	33 bd ff f8 	addiu	$sp, $sp, -8
+; CHECK-NEXT:    1e:	fb fd 00 00 	sw	$ra, 0($sp)
+; CHECK-NEXT:    22:	41 a1 00 01 	lui	$1, 1
+; CHECK-NEXT:    26:	40 60 00 02 	bal	8 <foo+0x2e>
+; CHECK-NEXT:    2a:	30 21 04 68 	addiu	$1, $1, 1128
+; CHECK-NEXT:    2e:	00 3f 09 50 	addu	$1, $ra, $1
+; CHECK-NEXT:    32:	ff fd 00 00 	lw	$ra, 0($sp)
+; CHECK-NEXT:    36:	00 01 0f 3c 	jr	$1
+; CHECK-NEXT:    3a:	33 bd 00 08 	addiu	$sp, $sp, 8
+; CHECK-NEXT:    3e:	94 00 00 02 	b	8 <foo+0x46>
+; CHECK-NEXT:    42:	00 00 00 00 	nop
+; CHECK-NEXT:    46:	30 20 4e 1f 	addiu	$1, $zero, 19999
+; CHECK-NEXT:    4a:	b4 22 00 14 	bne	$2, $1, 44 <foo+0x76>
+; CHECK-NEXT:    4e:	00 00 00 00 	nop
+; CHECK-NEXT:    52:	33 bd ff f8 	addiu	$sp, $sp, -8
+; CHECK-NEXT:    56:	fb fd 00 00 	sw	$ra, 0($sp)
+; CHECK-NEXT:    5a:	41 a1 00 01 	lui	$1, 1
+; CHECK-NEXT:    5e:	40 60 00 02 	bal	8 <foo+0x66>
+; CHECK-NEXT:    62:	30 21 04 5c 	addiu	$1, $1, 1116
+; CHECK-NEXT:    66:	00 3f 09 50 	addu	$1, $ra, $1
+; CHECK-NEXT:    6a:	ff fd 00 00 	lw	$ra, 0($sp)
+; CHECK-NEXT:    6e:	00 01 0f 3c 	jr	$1
+; CHECK-NEXT:    72:	33 bd 00 08 	addiu	$sp, $sp, 8
+; CHECK-NEXT:    76:	30 20 27 0f 	addiu	$1, $zero, 9999
+; CHECK-NEXT:    7a:	94 22 00 14 	beq	$2, $1, 44 <foo+0xa6>
+; CHECK-NEXT:    7e:	00 00 00 00 	nop
+; CHECK-NEXT:    82:	33 bd ff f8 	addiu	$sp, $sp, -8
+; CHECK-NEXT:    86:	fb fd 00 00 	sw	$ra, 0($sp)
+; CHECK-NEXT:    8a:	41 a1 00 01 	lui	$1, 1
+; CHECK-NEXT:    8e:	40 60 00 02 	bal	8 <foo+0x96>
+; CHECK-NEXT:    92:	30 21 04 2c 	addiu	$1, $1, 1068
+; CHECK-NEXT:    96:	00 3f 09 50 	addu	$1, $ra, $1
+; CHECK-NEXT:    9a:	ff fd 00 00 	lw	$ra, 0($sp)
+; CHECK-NEXT:    9e:	00 01 0f 3c 	jr	$1
+; CHECK-NEXT:    a2:	33 bd 00 08 	addiu	$sp, $sp, 8
+
+; CHECK:      10466:	00 00 00 00 	nop
+; CHECK-NEXT: 1046a:	94 00 00 02 	b	8 <foo+0x10472>
+; CHECK-NEXT: 1046e:	00 00 00 00 	nop
+; CHECK-NEXT: 10472:	33 bd ff f8 	addiu	$sp, $sp, -8
+; CHECK-NEXT: 10476:	fb fd 00 00 	sw	$ra, 0($sp)
+; CHECK-NEXT: 1047a:	41 a1 00 01 	lui	$1, 1
+; CHECK-NEXT: 1047e:	40 60 00 02 	bal	8 <foo+0x10486>
+; CHECK-NEXT: 10482:	30 21 04 00 	addiu	$1, $1, 1024
+; CHECK-NEXT: 10486:	00 3f 09 50 	addu	$1, $ra, $1
+; CHECK-NEXT: 1048a:	ff fd 00 00 	lw	$ra, 0($sp)
+; CHECK-NEXT: 1048e:	00 01 0f 3c 	jr	$1
+; CHECK-NEXT: 10492:	33 bd 00 08 	addiu	$sp, $sp, 8
+; CHECK-NEXT: 10496:	94 00 00 02 	b	8 <foo+0x1049e>
+
+@x = external global i32, align 4
+
+define void @foo() {
+  %1 = load i32, i32* @x, align 4
+  %2 = icmp sgt i32 %1, 0
+  br i1 %2, label %la, label %lf
+
+la:
+  switch i32 %1, label %le [
+    i32 9999, label %lb
+    i32 19999, label %lc
+  ]
+
+lb:
+  tail call void asm sideeffect ".space 0", ""()
+  br label %le
+
+lc:
+  tail call void asm sideeffect ".space 0", ""()
+  br label %le
+
+le:
+  tail call void asm sideeffect ".space 66500", ""()
+  br label %lg
+
+lf:
+  tail call void asm sideeffect ".space 0", ""()
+  br label %lg
+
+lg:
+  tail call void asm sideeffect ".space 0", ""()
+  br label %li
+
+li:
+  tail call void asm sideeffect ".space 0", ""()
+  ret void
+}