[PATCH] D88823: [CodeGen][TailDuplicator] Don't duplicate blocks with INLINEASM_BR

[Bill Wendling via Phabricator via llvm-commits]

void updated this revision to Diff 296237.
void added a comment.

Add testcase.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D88823/new/

https://reviews.llvm.org/D88823

Files:
  llvm/lib/CodeGen/TailDuplicator.cpp
  llvm/test/CodeGen/X86/tail-dup-asm-goto.ll


Index: llvm/test/CodeGen/X86/tail-dup-asm-goto.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/tail-dup-asm-goto.ll
@@ -0,0 +1,64 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+; RUN: llc -mtriple=x86_64-linux -stop-after=early-tailduplication < %s | FileCheck %s
+
+; Ensure that we don't duplicate a block with an "INLINEASM_BR" instruction
+; during code gen.
+
+declare void @foo()
+
+define i8* @test1() {
+  ; CHECK-LABEL: name: test1
+  ; CHECK: bb.0.bb:
+  ; CHECK:   successors: %bb.1(0x40000000), %bb.2(0x40000000)
+  ; CHECK:   [[DEF:%[0-9]+]]:gr64 = IMPLICIT_DEF
+  ; CHECK:   [[MOV64rm:%[0-9]+]]:gr64 = MOV64rm killed [[DEF]], 1, $noreg, 0, $noreg :: (load 8 from `i8** undef`)
+  ; CHECK:   [[MOV32r0_:%[0-9]+]]:gr32 = MOV32r0 implicit-def dead $eflags
+  ; CHECK:   [[COPY:%[0-9]+]]:gr8 = COPY [[MOV32r0_]].sub_8bit
+  ; CHECK:   TEST8rr [[COPY]], [[COPY]], implicit-def $eflags
+  ; CHECK:   JCC_1 %bb.2, 5, implicit $eflags
+  ; CHECK:   JMP_1 %bb.1
+  ; CHECK: bb.1.bb100:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   [[DEF1:%[0-9]+]]:gr64 = IMPLICIT_DEF
+  ; CHECK:   MOV64mi32 killed [[DEF1]], 1, $noreg, 0, $noreg, 0 :: (store 8 into `i8** undef`)
+  ; CHECK:   JMP_1 %bb.3
+  ; CHECK: bb.2.bb106:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK:   CALL64pcrel32 @foo, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp
+  ; CHECK:   ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+  ; CHECK:   [[MOV32r0_1:%[0-9]+]]:gr32 = MOV32r0 implicit-def dead $eflags
+  ; CHECK:   [[SUBREG_TO_REG:%[0-9]+]]:gr64 = SUBREG_TO_REG 0, killed [[MOV32r0_1]], %subreg.sub_32bit
+  ; CHECK: bb.3.bb110:
+  ; CHECK:   successors: %bb.5(0x80000000), %bb.4(0x00000000)
+  ; CHECK:   [[PHI:%[0-9]+]]:gr64 = PHI [[SUBREG_TO_REG]], %bb.2, [[MOV64rm]], %bb.1
+  ; CHECK:   INLINEASM_BR &"", 9 /* sideeffect mayload attdialect */, 13 /* imm */, 42, 13 /* imm */, 0, 13 /* imm */, blockaddress(@test1, %ir-block.bb17.i.i.i), 12 /* clobber */, implicit-def early-clobber $df, 12 /* clobber */, implicit-def early-clobber $fpsw, 12 /* clobber */, implicit-def early-clobber $eflags
+  ; CHECK:   JMP_1 %bb.5
+  ; CHECK: bb.4.bb17.i.i.i (address-taken):
+  ; CHECK:   successors: %bb.5(0x80000000)
+  ; CHECK: bb.5.kmem_cache_has_cpu_partial.exit:
+  ; CHECK:   $rax = COPY [[PHI]]
+  ; CHECK:   RET 0, $rax
+bb:
+  %i28.i = load i8*, i8** undef, align 8
+  br i1 undef, label %bb100, label %bb106
+
+bb100:                                            ; preds = %bb
+  store i8* null, i8** undef, align 8
+  br label %bb110
+
+bb106:                                            ; preds = %bb
+  call void @foo()
+  br label %bb110
+
+bb110:                                            ; preds = %bb106, %bb100
+  %i10.1 = phi i8* [ null, %bb106 ], [ %i28.i, %bb100 ]
+  callbr void asm sideeffect "", "i,i,X,~{dirflag},~{fpsr},~{flags}"(i32 42, i1 false, i8* blockaddress(@test1, %bb17.i.i.i))
+          to label %kmem_cache_has_cpu_partial.exit [label %bb17.i.i.i]
+
+bb17.i.i.i:                                       ; preds = %bb110
+  br label %kmem_cache_has_cpu_partial.exit
+
+kmem_cache_has_cpu_partial.exit:                  ; preds = %bb110
+  ret i8* %i10.1
+}
Index: llvm/lib/CodeGen/TailDuplicator.cpp
===================================================================
--- llvm/lib/CodeGen/TailDuplicator.cpp
+++ llvm/lib/CodeGen/TailDuplicator.cpp
@@ -627,6 +627,14 @@
     if (PreRegAlloc && MI.isCall())
       return false;
 
+    // Copying a block with an INLINEASM_BR instruction may result in a PHI node
+    // on the indirect path. We assume that all values used on the indirect path
+    // dominates all paths into the indirect block, i.e. don't have PHI nodes.
+    // FIXME: This may be too restrictive. Perhaps should restrict only if a
+    //        value in the current block isn't used on the indirect path.
+    if (MI.getOpcode() == TargetOpcode::INLINEASM_BR)
+      return false;
+
     if (MI.isBundle())
       InstrCount += MI.getBundleSize();
     else if (!MI.isPHI() && !MI.isMetaInstruction())


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