[Mips][FastISel] Fix selectBranch on icmp i1

[draganm]

Summary

The rL337288 tried to fix result of icmp i1 when its input is not sanitized by
falling back to DagISel. While it now produces the correct result for bit 0,
the other bits can still hold arbitrary value which isn't supported by
MipsFastISel branch lowering. This patch fixes the issue by falling
back to DagISel in this case.

[atanasyan]

LGTM

[atanasyan]

Do you have commit access?

[draganm]

No, I do not have it.

[draganm]

Sorry, I still have to delete some redundant empty lines. I believe that @petarj will commit it later.

lib/Target/Mips/MipsFastISel.cpp

bool MipsFastISel::selectBranch(const Instruction *I) {
   // if (cond) goto TBB
   // goto FBB
   // TBB:
   //
   MachineBasicBlock *TBB = FuncInfo.MBBMap[BI->getSuccessor(0)];
   MachineBasicBlock *FBB = FuncInfo.MBBMap[BI->getSuccessor(1)];
   // For now, just try the simplest case where it's fed by a compare.
   if (const CmpInst *CI = dyn_cast<CmpInst>(BI->getCondition())) {
+
+    MVT CIMVT =
+        TLI.getValueType(DL, CI->getOperand(0)->getType(), true).getSimpleVT();
+
+    if (CIMVT == MVT::i1)
+      return false;
+
     unsigned CondReg = getRegForValue(CI);
     BuildMI(*BrBB, FuncInfo.InsertPt, DbgLoc, TII.get(Mips::BGTZ))
         .addReg(CondReg)
         .addMBB(TBB);
     finishCondBranch(BI->getParent(), TBB, FBB);
     return true;
   }
   return false;

test/CodeGen/Mips/Fast-ISel/bricmpi1.ll

+; RUN: llc -march=mipsel -relocation-model=pic -O0 -fast-isel=true -mcpu=mips32r2 \
+; RUN:     < %s -verify-machineinstrs | FileCheck %s
+
+define void @testeq(i32, i32) {
+; CHECK-LABEL: testeq:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       beq $[[REG0]], $[[REG1]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp eq i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testne(i32, i32) {
+; CHECK-LABEL: testne:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       bne $[[REG0]], $[[REG1]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp ne i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testugt(i32, i32) {
+; CHECK-LABEL: testugt:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       sltu $[[REG2:[0-9]+]], $[[REG1]], $[[REG0]]
+; CHECK:       bnez $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp ugt i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testuge(i32, i32) {
+; CHECK-LABEL: testuge:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       sltu $[[REG2:[0-9]+]], $[[REG0]], $[[REG1]]
+; CHECK:       beqz $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp uge i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testult(i32, i32) {
+; CHECK-LABEL: testult:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       sltu $[[REG2:[0-9]+]], $[[REG0]], $[[REG1]]
+; CHECK:       bnez $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp ult i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testule(i32, i32) {
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       sltu $[[REG2:[0-9]+]], $[[REG1]], $[[REG0]]
+; CHECK:       beqz $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp ule i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testsgt(i32, i32) {
+; CHECK-LABEL: testsgt:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       negu $[[REG0]], $[[REG0]]
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       negu $[[REG1]], $[[REG1]]
+; CHECK:       slt $[[REG2:[0-9]+]], $[[REG1]], $[[REG0]]
+; CHECK:       bnez $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp sgt i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testsge(i32, i32) {
+; CHECK-LABEL: testsge:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       negu $[[REG0]], $[[REG0]]
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       negu $[[REG1]], $[[REG1]]
+; CHECK:       slt $[[REG2:[0-9]+]], $[[REG0]], $[[REG1]]
+; CHECK:       beqz $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp sge i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testslt(i32, i32) {
+; CHECK-LABEL: testslt:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       negu $[[REG0]], $[[REG0]]
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       negu $[[REG1]], $[[REG1]]
+; CHECK:       slt $[[REG2:[0-9]+]], $[[REG0]], $[[REG1]]
+; CHECK:       bnez $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp slt i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+define void @testsle(i32, i32) {
+; CHECK-LABEL: testsle:
+; CHECK:       andi $[[REG0:[0-9]+]], $4, 1
+; CHECK:       negu $[[REG0]], $[[REG0]]
+; CHECK:       andi $[[REG1:[0-9]+]], $5, 1
+; CHECK:       negu $[[REG1]], $[[REG1]]
+; CHECK:       slt $[[REG2:[0-9]+]], $[[REG1]], $[[REG0]]
+; CHECK:       beqz $[[REG2]],
+  %3 = trunc i32 %0 to i1
+  %4 = trunc i32 %1 to i1
+  %5 = icmp sle i1 %3, %4
+  br i1 %5, label %end, label %trap
+trap:
+  call void @llvm.trap()
+  br label %end
+end:
+  ret void
+}
+
+
+declare void @llvm.trap()