136 lines
5.7 KiB
Diff
136 lines
5.7 KiB
Diff
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From 3b777f98a3997f338919af7ff1ef8a6fd07f76a0 Mon Sep 17 00:00:00 2001
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From: Fangrui Song <i@maskray.me>
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Date: Wed, 16 Aug 2023 23:11:59 -0700
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Subject: [PATCH 14/14] [Mips][MC] AttemptToFoldSymbolOffsetDifference: revert
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isMicroMips special case
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D52985/D57677 added a .gcc_except_table workaround, but the new behavior
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doesn't match GNU assembler.
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```
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void foo();
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int bar() {
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foo();
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try { throw 1; }
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catch (int) { return 1; }
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return 0;
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}
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clang --target=mipsel-linux-gnu -mmicromips -S a.cc
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mipsel-linux-gnu-gcc -mmicromips -c a.s -o gnu.o
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.uleb128 ($cst_end0)-($cst_begin0) // bit 0 is not forced to 1
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.uleb128 ($func_begin0)-($func_begin0) // bit 0 is not forced to 1
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```
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I have inspected `.gcc_except_table` output by `mipsel-linux-gnu-gcc -mmicromips -c a.cc`.
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The `.uleb128` values are not forced to set the least significant bit.
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In addition, D57677's adjustment (even->odd) to CodeGen/Mips/micromips-b-range.ll is wrong.
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PC-relative `.long func - .` values will differ from GNU assembler as well.
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The original intention of D52985 seems unclear to me. I think whatever
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goal it wants to achieve should be moved to an upper layer.
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This isMicroMips special case has caused problems to fix MCAssembler::relaxLEB to use evaluateAsAbsolute instead of evaluateKnownAbsolute,
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which is needed to proper support R_RISCV_SET_ULEB128/R_RISCV_SUB_ULEB128.
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Differential Revision: https://reviews.llvm.org/D157655
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(cherry picked from commit 4c89277095ee7cda3d20e0f5f18b384212069778)
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Change-Id: Iedd73e0c61856c30fde442309fc16d4327829f1a
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---
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llvm/lib/MC/MCExpr.cpp | 5 -----
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llvm/test/CodeGen/Mips/micromips-b-range.ll | 8 ++++----
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llvm/test/CodeGen/Mips/micromips-gcc-except-table.ll | 2 +-
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llvm/test/DebugInfo/Mips/eh_frame.ll | 4 ++--
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4 files changed, 7 insertions(+), 12 deletions(-)
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diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
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index 79808a58d81c..c9ff1865cf91 100644
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--- a/llvm/lib/MC/MCExpr.cpp
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+++ b/llvm/lib/MC/MCExpr.cpp
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@@ -611,11 +611,6 @@ static void AttemptToFoldSymbolOffsetDifference(
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if (Asm->isThumbFunc(&SA))
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Addend |= 1;
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- // If symbol is labeled as micromips, we set low-bit to ensure
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- // correct offset in .gcc_except_table
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- if (Asm->getBackend().isMicroMips(&SA))
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- Addend |= 1;
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-
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// Clear the symbol expr pointers to indicate we have folded these
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// operands.
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A = B = nullptr;
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diff --git a/llvm/test/CodeGen/Mips/micromips-b-range.ll b/llvm/test/CodeGen/Mips/micromips-b-range.ll
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index 064afff3da0e..81d1c04208cc 100644
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--- a/llvm/test/CodeGen/Mips/micromips-b-range.ll
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+++ b/llvm/test/CodeGen/Mips/micromips-b-range.ll
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@@ -13,7 +13,7 @@
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; CHECK-NEXT: 1e: fb fd 00 00 sw $ra, 0($sp)
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; CHECK-NEXT: 22: 41 a1 00 01 lui $1, 1
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; CHECK-NEXT: 26: 40 60 00 02 bal 0x2e <foo+0x2e>
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-; CHECK-NEXT: 2a: 30 21 04 69 addiu $1, $1, 1129
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+; CHECK-NEXT: 2a: 30 21 04 68 addiu $1, $1, 1128
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; CHECK-NEXT: 2e: 00 3f 09 50 addu $1, $ra, $1
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; CHECK-NEXT: 32: ff fd 00 00 lw $ra, 0($sp)
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; CHECK-NEXT: 36: 00 01 0f 3c jr $1
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@@ -27,7 +27,7 @@
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; CHECK-NEXT: 56: fb fd 00 00 sw $ra, 0($sp)
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; CHECK-NEXT: 5a: 41 a1 00 01 lui $1, 1
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; CHECK-NEXT: 5e: 40 60 00 02 bal 0x66 <foo+0x66>
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-; CHECK-NEXT: 62: 30 21 04 5d addiu $1, $1, 1117
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+; CHECK-NEXT: 62: 30 21 04 5c addiu $1, $1, 1116
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; CHECK-NEXT: 66: 00 3f 09 50 addu $1, $ra, $1
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; CHECK-NEXT: 6a: ff fd 00 00 lw $ra, 0($sp)
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; CHECK-NEXT: 6e: 00 01 0f 3c jr $1
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@@ -39,7 +39,7 @@
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; CHECK-NEXT: 86: fb fd 00 00 sw $ra, 0($sp)
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; CHECK-NEXT: 8a: 41 a1 00 01 lui $1, 1
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; CHECK-NEXT: 8e: 40 60 00 02 bal 0x96 <foo+0x96>
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-; CHECK-NEXT: 92: 30 21 04 2d addiu $1, $1, 1069
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+; CHECK-NEXT: 92: 30 21 04 2c addiu $1, $1, 1068
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; CHECK-NEXT: 96: 00 3f 09 50 addu $1, $ra, $1
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; CHECK-NEXT: 9a: ff fd 00 00 lw $ra, 0($sp)
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; CHECK-NEXT: 9e: 00 01 0f 3c jr $1
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@@ -51,7 +51,7 @@
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; CHECK-NEXT: 10476: fb fd 00 00 sw $ra, 0($sp)
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; CHECK-NEXT: 1047a: 41 a1 00 01 lui $1, 1
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; CHECK-NEXT: 1047e: 40 60 00 02 bal 0x10486 <foo+0x10486>
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-; CHECK-NEXT: 10482: 30 21 04 01 addiu $1, $1, 1025
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+; CHECK-NEXT: 10482: 30 21 04 00 addiu $1, $1, 1024
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; CHECK-NEXT: 10486: 00 3f 09 50 addu $1, $ra, $1
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; CHECK-NEXT: 1048a: ff fd 00 00 lw $ra, 0($sp)
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; CHECK-NEXT: 1048e: 00 01 0f 3c jr $1
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diff --git a/llvm/test/CodeGen/Mips/micromips-gcc-except-table.ll b/llvm/test/CodeGen/Mips/micromips-gcc-except-table.ll
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index 2b63aff01574..20d64fc216b7 100644
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--- a/llvm/test/CodeGen/Mips/micromips-gcc-except-table.ll
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+++ b/llvm/test/CodeGen/Mips/micromips-gcc-except-table.ll
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@@ -1,7 +1,7 @@
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; RUN: llc -mtriple=mips-linux-gnu -mcpu=mips32r2 -mattr=+micromips -O3 -filetype=obj < %s | llvm-objdump -s -j .gcc_except_table - | FileCheck %s
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; CHECK: Contents of section .gcc_except_table:
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-; CHECK-NEXT: 0000 ff9b1501 0c011100 00110e1f 011f1800
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+; CHECK-NEXT: 0000 ff9b1501 0c001000 00100e1e 011e1800
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; CHECK-NEXT: 0010 00010000 00000000
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@_ZTIi = external constant ptr
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diff --git a/llvm/test/DebugInfo/Mips/eh_frame.ll b/llvm/test/DebugInfo/Mips/eh_frame.ll
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index 506e5b87892b..60d4dc76777e 100644
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--- a/llvm/test/DebugInfo/Mips/eh_frame.ll
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+++ b/llvm/test/DebugInfo/Mips/eh_frame.ll
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@@ -26,9 +26,9 @@
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; CHECK-READELF-PIC-NEXT: R_MIPS_PC32
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; CHECK-READELF-NEXT: .gcc_except_table
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-; EXCEPT-TABLE-STATIC: 0000 ff9b1501 0c011500 00150e23 01231e00 ...........#.#..
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+; EXCEPT-TABLE-STATIC: 0000 ff9b1501 0c001400 00140e22 01221e00 ..........."."..
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; EXCEPT-TABLE-STATIC: 0010 00010000 00000000
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-; EXCEPT-TABLE-PIC: 0000 ff9b1501 0c012d00 002d133f 013f2a00 ......-..-.?.?*.
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+; EXCEPT-TABLE-PIC: 0000 ff9b1501 0c002c00 002c123e 013e2a00 ......,..,.>.>*.
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; EXCEPT-TABLE-PIC: 0010 00010000 00000000 ........
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@_ZTIi = external constant ptr
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--
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2.20.1
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