Coalescer should not delete extract_subreg, insert_subreg, and subreg_to_reg of

physical registers. This is especially critical for the later two since they
start the live interval of a super-register. e.g.
%DO<def> = INSERT_SUBREG %D0<undef>, %S0<kill>, 1
If this instruction is eliminated, the register scavenger will not be happy as
D0 is not defined previously.
This fixes PR5055.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82968 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SimpleRegisterCoalescing.cpp

@@ -2692,21 +2692,34 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
       unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
       if (JoinedCopies.count(MI)) {
         // Delete all coalesced copies.
+        bool DoDelete = true;
         if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
           assert((MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
                   MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
                   MI->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) &&
                  "Unrecognized copy instruction");
           DstReg = MI->getOperand(0).getReg();
+          if (TargetRegisterInfo::isPhysicalRegister(DstReg))
+            // Do not delete extract_subreg, insert_subreg of physical
+            // registers unless the definition is dead. e.g.
+            // %DO<def> = INSERT_SUBREG %D0<undef>, %S0<kill>, 1
+            // or else the scavenger may complain. LowerSubregs will
+            // change this to an IMPLICIT_DEF later.
+            DoDelete = false;
         }
         if (MI->registerDefIsDead(DstReg)) {
           LiveInterval &li = li_->getInterval(DstReg);
           if (!ShortenDeadCopySrcLiveRange(li, MI))
             ShortenDeadCopyLiveRange(li, MI);
+          DoDelete = true;
+        }
+        if (!DoDelete)
+          mii = next(mii);
+        else {
+          li_->RemoveMachineInstrFromMaps(MI);
+          mii = mbbi->erase(mii);
+          ++numPeep;
         }
-        li_->RemoveMachineInstrFromMaps(MI);
-        mii = mbbi->erase(mii);
-        ++numPeep;
         continue;
       }
 

test/CodeGen/ARM/2009-09-27-CoalescerBug.ll

@@ -0,0 +1,24 @@
+; RUN: llc < %s -mtriple=armv7-eabi -mcpu=cortex-a8
+; PR5055
+
+module asm ".globl\09__aeabi_f2lz"
+module asm ".set\09__aeabi_f2lz, __fixsfdi"
+module asm ""
+
+define arm_aapcs_vfpcc i64 @__fixsfdi(float %a) nounwind {
+entry:
+  %0 = fcmp olt float %a, 0.000000e+00            ; <i1> [#uses=1]
+  br i1 %0, label %bb, label %bb1
+
+bb:                                               ; preds = %entry
+  %1 = fsub float -0.000000e+00, %a               ; <float> [#uses=1]
+  %2 = tail call arm_aapcs_vfpcc  i64 @__fixunssfdi(float %1) nounwind ; <i64> [#uses=1]
+  %3 = sub i64 0, %2                              ; <i64> [#uses=1]
+  ret i64 %3
+
+bb1:                                              ; preds = %entry
+  %4 = tail call arm_aapcs_vfpcc  i64 @__fixunssfdi(float %a) nounwind ; <i64> [#uses=1]
+  ret i64 %4
+}
+
+declare arm_aapcs_vfpcc i64 @__fixunssfdi(float)

test/CodeGen/Blackfin/2009-08-15-LiveIn-SubReg.ll

@@ -1,5 +1,4 @@
 ; RUN: llc < %s -march=bfin -verify-machineinstrs
-; XFAIL: *
 
 ; When joining live intervals of sub-registers, an MBB live-in list is not
 ; updated properly. The register scavenger asserts on an undefined register.

test/CodeGen/X86/sink-hoist.ll

@@ -7,7 +7,7 @@
 
 ; CHECK: foo:
 ; CHECK-NEXT: divsd
-; CHECK-NEXT: testb $1, %dil
+; CHECK:      testb $1, %dil
 ; CHECK-NEXT: jne
 
 define double @foo(double %x, double %y, i1 %c) nounwind {