[PATCH] D93158: [X86] Avoid %fs:(%eax) references in x32 mode

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: llvm/lib/Target/X86/X86ISelDAGToDAG.cpp:1618
+bool X86DAGToDAGISel::matchLoadInAddress(LoadSDNode *N, X86ISelAddressMode &AM,
+                                         bool NoRegisters) {
   SDValue Address = N->getOperand(1);
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hvdijk wrote:
> RKSimon wrote:
> > Is there a better name that we can use than NoRegisters?
> I was thinking of something like `AllowSegmentReg` initially, but that would be a poor name, since except for X32, segment registers are always allowed. I picked `NoRegisters` to reflect that when `NoRegisters` is true, it is known that `AM` does not and will not refer to any registers other than what `matchLoadInAddress` does. I now see that that is not entirely true either, as `AM` may in theory already reference another segment register. `NoBaseReg` would be slightly more accurate, but still not very clear. Perhaps I should go back to what I originally had and change it to the slightly verbose but pretty clear `AllowSegmentRegForX32`?
Something X32 specific would be better - so AllowSegmentRegForX32 would be fine.


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Comment at: llvm/test/CodeGen/X86/pic.ll:339
 ; CHECK-X32-DAG:	movl	%fs:0,
-; CHECK:	addl
+; CHECK:	{{addl|leal \(%.*,%.*\),}}
 ; CHECK-I686:	movl	tlsptrie at GOTNTPOFF(
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it doesn't look great to allow add or lea like this - maybe add an additional CHECK-X32-ISEL/CHECK-X32-FAST prefix and check them properly?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93158/new/

https://reviews.llvm.org/D93158