[PATCH] D88496: [ARM] Fix IT block generation after Thumb2SizeReduce with -Oz

[Nicholas Guy via Phabricator via llvm-commits]

NickGuy updated this revision to Diff 301605.
NickGuy added a comment.

I appreciate that the history and context for this has been a bit obscured. Most of it can be gathered on the patch D83667 <https://reviews.llvm.org/D83667>

> can you upload a diff with just the changes ?

Done


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88496/new/

https://reviews.llvm.org/D88496

Files:
  llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
  llvm/test/CodeGen/Thumb2/constant-hoisting.ll
  llvm/test/CodeGen/Thumb2/ifcvt-dead-predicate.mir


Index: llvm/test/CodeGen/Thumb2/ifcvt-dead-predicate.mir
===================================================================
--- llvm/test/CodeGen/Thumb2/ifcvt-dead-predicate.mir
+++ llvm/test/CodeGen/Thumb2/ifcvt-dead-predicate.mir
@@ -45,15 +45,13 @@
 body:             |
   ; CHECK-LABEL: name: branch_entry
   ; CHECK: bb.0.entry:
-  ; CHECK:   successors: %bb.1, %bb.2
+  ; CHECK:   successors: %bb.1
   ; CHECK:   liveins: $r0, $r1, $r2
   ; CHECK:   renamable $r0 = tLDRBi killed renamable $r0, 0, 14 /* CC::al */, $noreg :: (load 1 from %ir.command_set, align 4)
   ; CHECK:   dead renamable $r0, $cpsr = tLSLri killed renamable $r0, 24, 14 /* CC::al */, $noreg
-  ; CHECK:   t2Bcc %bb.2, 4 /* CC::mi */, killed $cpsr
-  ; CHECK: bb.1.land.end:
-  ; CHECK:   $r0, dead $cpsr = tMOVi8 0, 14 /* CC::al */, $noreg
-  ; CHECK:   tBX_RET 14 /* CC::al */, $noreg, implicit $r0
-  ; CHECK: bb.2.land.rhs:
+  ; CHECK:   $r0, dead $noreg = tMOVi8 0, 5 /* CC::pl */, $cpsr
+  ; CHECK:   tBX_RET 5 /* CC::pl */, killed $cpsr, implicit killed $r0
+  ; CHECK: bb.1.land.rhs:
   ; CHECK:   liveins: $r1, $r2
   ; CHECK:   $r0 = tMOVr killed $r1, 14 /* CC::al */, $noreg
   ; CHECK:   $r1 = tMOVr killed $r2, 14 /* CC::al */, $noreg
Index: llvm/test/CodeGen/Thumb2/constant-hoisting.ll
===================================================================
--- llvm/test/CodeGen/Thumb2/constant-hoisting.ll
+++ llvm/test/CodeGen/Thumb2/constant-hoisting.ll
@@ -39,9 +39,17 @@
 ; CHECK-V7M-NEXT:    cmp r2, #50
 ; CHECK-V7M-NEXT:    beq .LBB0_5
 ; CHECK-V7M-NEXT:    cmp r2, #1
-; CHECK-V7M-NEXT:    beq .LBB0_7
+; CHECK-V7M-NEXT:    ittt eq
+; CHECK-V7M-NEXT:    addeq r0, r1
+; CHECK-V7M-NEXT:    addeq r0, #1
+; CHECK-V7M-NEXT:    bxeq lr
+; CHECK-V7M-NEXT:  .LBB0_2:
 ; CHECK-V7M-NEXT:    cmp r2, #30
-; CHECK-V7M-NEXT:    beq .LBB0_8
+; CHECK-V7M-NEXT:    ittt eq
+; CHECK-V7M-NEXT:    addeq r0, r1
+; CHECK-V7M-NEXT:    addeq r0, #2
+; CHECK-V7M-NEXT:    bxeq lr
+; CHECK-V7M-NEXT:  .LBB0_3:
 ; CHECK-V7M-NEXT:    cbnz r2, .LBB0_6
 ; CHECK-V7M-NEXT:    add r0, r1
 ; CHECK-V7M-NEXT:    bx lr
@@ -50,14 +58,6 @@
 ; CHECK-V7M-NEXT:    adds r0, #4
 ; CHECK-V7M-NEXT:  .LBB0_6:
 ; CHECK-V7M-NEXT:    bx lr
-; CHECK-V7M-NEXT:  .LBB0_7:
-; CHECK-V7M-NEXT:    add r0, r1
-; CHECK-V7M-NEXT:    adds r0, #1
-; CHECK-V7M-NEXT:    bx lr
-; CHECK-V7M-NEXT:  .LBB0_8:
-; CHECK-V7M-NEXT:    add r0, r1
-; CHECK-V7M-NEXT:    adds r0, #2
-; CHECK-V7M-NEXT:    bx lr
 ; CHECK-V7M-NEXT:    .p2align 2
 ; CHECK-V7M-NEXT:  .LCPI0_0:
 ; CHECK-V7M-NEXT:    .long 537923600
Index: llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -603,8 +603,17 @@
   bool Found = false;
   for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
     const MachineOperand &MO = MI.getOperand(i);
-    if ((MO.isRegMask() && MO.clobbersPhysReg(ARM::CPSR)) ||
-        (MO.isReg() && MO.isDef() && MO.getReg() == ARM::CPSR)) {
+    bool ClobbersCPSR = MO.isRegMask() && MO.clobbersPhysReg(ARM::CPSR);
+    bool IsCPSR = MO.isReg() && MO.isDef() && MO.getReg() == ARM::CPSR;
+    if (ClobbersCPSR || IsCPSR) {
+
+      // Filter out T1 instructions that have a dead CPSR,
+      // allowing IT blocks to be generated containing T1 instructions
+      const MCInstrDesc &MCID = MI.getDesc();
+      if (MCID.TSFlags & ARMII::ThumbArithFlagSetting && MO.isDead() &&
+          SkipDead)
+        continue;
+
       Pred.push_back(MO);
       Found = true;
     }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D88496.301605.patch
Type: text/x-patch
Size: 3572 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20201029/7d53b5df/attachment-0001.bin>