Fix not correct imm operand assertion for SUB32ri in X86CondBrFolding::analyzeCompare

[craig.topper]

Summary

When doing X86CondBrFolding::analyzeCompare, it will meet the SUB32ri instruction as below to use the global address for its operand,

%733:gr32 = SUB32ri %62:gr32(tied-def 0), @img2buf_normal, implicit-def $eflags
JNE_1 %bb.41, implicit $eflags

so the assertion "assert(MI.getOperand(ValueIndex).isImm() && "Expecting Imm operand")" is not correct and change the assert to if make X86CondBrFolding::analyzeCompare return false as not finding the compare for this

[Jianping]

update diff with format-patch -U999999

[Jianping]

Anything that I need to follow up on this code review ? Thanks

[lebedev.ri]

Test?

[Jianping]

This comment was removed by Jianping.

[Jianping]

to reproduce this assertion , need to register the X86CondBrFoldingPass to make it can be run with llc --run-pass X86CondBrFolding on small mir test case, please look at https://reviews.llvm.org/D55412

Thanks

[craig.topper]

Commandeering so I can rebase this relative to D55412.

[craig.topper]

Rebase to include the test file from the other patch with the XFAIL removed.

[Jianping]

Thanks

lib/Target/X86/X86CondBrFolding.cpp

bool X86CondBrFolding::analyzeCompare(const MachineInstr &MI, unsigned &SrcReg,
   case X86::SUB16ri:
   case X86::SUB16ri8:
   case X86::SUB8ri:
     SrcRegIndex = 1;
     ValueIndex = 2;
     break;
   }
   SrcReg = MI.getOperand(SrcRegIndex).getReg();
-  assert(MI.getOperand(ValueIndex).isImm() && "Expecting Imm operand");
+  if (!MI.getOperand(ValueIndex).isImm())
+    return false;
   CmpValue = MI.getOperand(ValueIndex).getImm();
   return true;
 }
 
 // Analyze a candidate MBB and set the extract all the information needed.
 // The valid candidate will have two successors.
 // It also should have a sequence of
 //  Branch_instr,

test/CodeGen/X86/test_x86condbr_globaladdr.mir

+# RUN: llc -o - %s -mtriple=i686-- -mcpu=ivybridge --run-pass X86CondBrFolding | FileCheck %s
+
+# Test wrong assertion when meet SUB32ri with global address
+# in X86CondBrFoldingiPass
+--- |
+  @img2buf_normal = external global i32
+  define void @func() { ret void }
+...
+---
+# CHECK: bb.0:
+# CHECK: %2:gr32 = SUB32ri %1, @img2buf_normal, implicit-def $eflags
+
+name: func
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $edx
+    %1:gr32 = COPY $edx
+    %2:gr32 = MOV32rm %1:gr32, 1, $noreg, 850256, $noreg
+    %3:gr32 = SUB32ri %2:gr32, @img2buf_normal, implicit-def $eflags
+    JE_1 %bb.2, implicit $eflags
+    JMP_1 %bb.3
+
+  bb.2:
+    RET 0, undef $eax
+
+  bb.3:
+    $eax = MOV32rr %3:gr32
+    RET 0, $eax
+...