[llvm] 1c68c4c - [LoongArch][MC] Modify branch evaluation for MCInstrAnalysis (#73205)

[via llvm-commits]

Author: ZhaoQi
Date: 2023-11-23T16:38:41+08:00
New Revision: 1c68c4c57a65a67963264878bc4646be8b58854c

URL: https://github.com/llvm/llvm-project/commit/1c68c4c57a65a67963264878bc4646be8b58854c
DIFF: https://github.com/llvm/llvm-project/commit/1c68c4c57a65a67963264878bc4646be8b58854c.diff

LOG: [LoongArch][MC] Modify branch evaluation for MCInstrAnalysis (#73205)

Function evaluateBranch() is used to compute target address for a given
branch instruction and return true on success. But target address of
indirect branch cannot be simply added, so rule it out and just return
false.

This patch also add objdump tests which capture the current state of
support for printing branch targets. Without this patch, the result of
"jirl $zero, $a0, 4" is "jirl $zero, $a0, 4 <foo+0x64>". It is obviously
incorrect, because this instruction represents an indirect branch whose
target address depends on both the register value and the imm. After
this patch, it will be right despite loss of details.

Added: 
    llvm/test/tools/llvm-objdump/ELF/LoongArch/branches.s
    llvm/test/tools/llvm-objdump/ELF/LoongArch/lit.local.cfg

Modified: 
    llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.cpp b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.cpp
index d580c3457fecff8..a4e6a09863e6a68 100644
--- a/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.cpp
+++ b/llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchMCTargetDesc.cpp
@@ -97,7 +97,8 @@ class LoongArchMCInstrAnalysis : public MCInstrAnalysis {
   bool evaluateBranch(const MCInst &Inst, uint64_t Addr, uint64_t Size,
                       uint64_t &Target) const override {
     unsigned NumOps = Inst.getNumOperands();
-    if (isBranch(Inst) || Inst.getOpcode() == LoongArch::BL) {
+    if ((isBranch(Inst) && !isIndirectBranch(Inst)) ||
+        Inst.getOpcode() == LoongArch::BL) {
       Target = Addr + Inst.getOperand(NumOps - 1).getImm();
       return true;
     }

diff  --git a/llvm/test/tools/llvm-objdump/ELF/LoongArch/branches.s b/llvm/test/tools/llvm-objdump/ELF/LoongArch/branches.s
new file mode 100644
index 000000000000000..8cb00aef9954272
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/ELF/LoongArch/branches.s
@@ -0,0 +1,76 @@
+# RUN: llvm-mc --triple=loongarch32 --filetype=obj < %s | \
+# RUN:   llvm-objdump -d --no-show-raw-insn - | FileCheck %s
+# RUN: llvm-mc --triple=loongarch64 --filetype=obj < %s | \
+# RUN:   llvm-objdump -d --no-show-raw-insn - | FileCheck %s
+
+# CHECK-LABEL: <foo>:
+foo:
+# CHECK: beq $a0, $a1, 108 <foo+0x6c>
+beq $a0, $a1, .Llocal
+# CHECK: bne $a0, $a1, 104 <foo+0x6c>
+bne $a0, $a1, .Llocal
+# CHECK: blt $a0, $a1, 100 <foo+0x6c>
+blt $a0, $a1, .Llocal
+# CHECK: bltu $a0, $a1, 96 <foo+0x6c>
+bltu $a0, $a1, .Llocal
+# CHECK: bge $a0, $a1, 92 <foo+0x6c>
+bge $a0, $a1, .Llocal
+# CHECK: bgeu $a0, $a1, 88 <foo+0x6c>
+bgeu $a0, $a1, .Llocal
+# CHECK: beqz $a0, 84 <foo+0x6c>
+beqz $a0, .Llocal
+# CHECK: bnez $a0, 80 <foo+0x6c>
+bnez $a0, .Llocal
+# CHECK: bceqz $fcc6, 76 <foo+0x6c>
+bceqz $fcc6, .Llocal
+# CHECK: bcnez $fcc6, 72 <foo+0x6c>
+bcnez $fcc6, .Llocal
+
+# CHECK: beq $a0, $a1, 76 <bar>
+beq $a0, $a1, bar
+# CHECK: bne $a0, $a1, 72 <bar>
+bne $a0, $a1, bar
+# CHECK: blt $a0, $a1, 68 <bar>
+blt $a0, $a1, bar
+# CHECK: bltu $a0, $a1, 64 <bar>
+bltu $a0, $a1, bar
+# CHECK: bge $a0, $a1, 60 <bar>
+bge $a0, $a1, bar
+# CHECK: bgeu $a0, $a1, 56 <bar>
+bgeu $a0, $a1, bar
+# CHECK: beqz $a0, 52 <bar>
+beqz $a0, bar
+# CHECK: bnez $a0, 48 <bar>
+bnez $a0, bar
+# CHECK: bceqz $fcc6, 44 <bar>
+bceqz $fcc6, bar
+# CHECK: bcnez $fcc6, 40 <bar>
+bcnez $fcc6, bar
+
+# CHECK: b 28 <foo+0x6c>
+b .Llocal
+# CHECK: b 32 <bar>
+b bar
+
+# CHECK: bl 20 <foo+0x6c>
+bl .Llocal
+# CHECK: bl 24 <bar>
+bl bar
+
+# CHECK: jirl $zero, $a0, 4{{$}}
+jirl $zero, $a0, 4
+# CHECK: jirl $ra, $a0, 4{{$}}
+jirl $ra, $a0, 4
+# CHECK: ret
+ret
+
+.Llocal:
+# CHECK: 6c: nop
+# CHECK: nop
+nop
+nop
+
+# CHECK-LABEL: <bar>:
+bar:
+# CHECK: 74: nop
+nop

diff  --git a/llvm/test/tools/llvm-objdump/ELF/LoongArch/lit.local.cfg b/llvm/test/tools/llvm-objdump/ELF/LoongArch/lit.local.cfg
new file mode 100644
index 000000000000000..cc24278acbb414a
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/ELF/LoongArch/lit.local.cfg
@@ -0,0 +1,2 @@
+if not "LoongArch" in config.root.targets:
+    config.unsupported = True