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9d10d98e8b
If result of 64-bit address loading combines with 32-bit mask, LLVM
tries to optimize the code and remove "redundant" loading of upper
32-bits of the address. It leads to incorrect code on MIPS64 targets.
MIPS backend creates the following chain of commands to load 64-bit
address in the `MipsTargetLowering::getAddrNonPICSym64` method:
```
(add (shl (add (shl (add %highest(sym), %higher(sym)),
16),
%hi(sym)),
16),
%lo(%sym))
```
If the mask presents, LLVM decides to optimize the chain of commands. It
really does not make sense to load upper 32-bits because the 0x0fffffff
mask anyway clears them. After removing redundant commands we get this
chain:
```
(add (shl (%hi(sym), 16), %lo(%sym))
```
There is no patterns matched `(MipsHi (i64 symbol))`. Due a bug in `SYM_32`
predicate definition, backend incorrectly selects a pattern for a 32-bit
symbols and uses the `lui` instruction for loading `%hi(sym)`.
As a result we get incorrect set of instructions with unnecessary 16-bit
left shifting:
```
lui at,0x0
R_MIPS_HI16 foo
dsll at,at,0x10
daddiu at,at,0
R_MIPS_LO16 foo
```
This patch resolves two problems:
- Fix `SYM_32/SYM_64` predicates to prevent selection of patterns dedicated
to 32-bit symbols in case of using N64 ABI.
- Add missed patterns for 64-bit symbols for `%hi/%lo`.
Fix PR42736.
Differential Revision: https://reviews.llvm.org/D66228
llvm-svn: 370268
29 lines
993 B
LLVM
29 lines
993 B
LLVM
; RUN: llc -mtriple=mips64-linux-gnuabi64 \
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; RUN: -relocation-model=pic < %s | FileCheck %s -check-prefix=PIC
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; RUN: llc -mtriple=mips64-linux-gnuabi64 \
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; RUN: -relocation-model=static < %s | FileCheck %s -check-prefix=STATIC
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define void @bar1() nounwind {
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entry:
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; PIC: lui $[[R0:[0-9]+]], 4095
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; PIC-NEXT: ori $[[R0]], $[[R0]], 65535
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; PIC-NEXT: ld $[[R1:[0-9]+]], %got_disp(foo)(${{[0-9]+}})
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; PIC-NEXT: and $[[R1]], $[[R1]], $[[R0]]
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; PIC-NEXT: sd $[[R1]]
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; STATIC: lui $[[R0:[0-9]+]], 4095
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; STATIC-NEXT: ori $[[R0]], $[[R0]], 65535
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; STATIC-NEXT: daddiu $[[R1:[0-9]+]], $zero, %hi(foo)
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; STATIC-NEXT: dsll $[[R1]], $[[R1]], 16
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; STATIC-NEXT: daddiu $[[R1]], $[[R1]], %lo(foo)
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; STATIC-NEXT: and $[[R0]], $[[R1]], $[[R0]]
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; STATIC-NEXT: sd $[[R0]]
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%val = alloca i64, align 8
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store i64 and (i64 ptrtoint (void ()* @foo to i64), i64 268435455), i64* %val, align 8
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%0 = load i64, i64* %val, align 8
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ret void
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}
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declare void @foo()
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