[PATCH] D60657: [RISCV] Fix evaluation of %pcrel_lo

[Roger Ferrer Ibanez via Phabricator via llvm-commits]

rogfer01 updated this revision to Diff 220293.
rogfer01 added a comment.

ChangeLog:

- Remove unneeded runtime check and turn it into an assertion.
- Avoid instruction aliases in testcase
- Strengthen check directives for the `NORELAX` case.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60657/new/

https://reviews.llvm.org/D60657

Files:
  llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
  llvm/test/MC/RISCV/pcrel-fixups.s


Index: llvm/test/MC/RISCV/pcrel-fixups.s
===================================================================
--- /dev/null
+++ llvm/test/MC/RISCV/pcrel-fixups.s
@@ -0,0 +1,52 @@
+# RUN: llvm-mc -triple riscv32 -mattr=-relax -filetype obj %s \
+# RUN:    | llvm-objdump -M no-aliases -d -r - \
+# RUN:    | FileCheck --check-prefix NORELAX %s
+# RUN: llvm-mc -triple riscv32 -mattr=+relax -filetype obj %s \
+# RUN:    | llvm-objdump -M no-aliases -d -r - \
+# RUN:    | FileCheck --check-prefix RELAX %s
+# RUN: llvm-mc -triple riscv64 -mattr=-relax -filetype obj %s \
+# RUN:    | llvm-objdump -M no-aliases -d -r - \
+# RUN:    | FileCheck --check-prefix NORELAX %s
+# RUN: llvm-mc -triple riscv64 -mattr=+relax -filetype obj %s \
+# RUN:    | llvm-objdump -M no-aliases -d -r - \
+# RUN:    | FileCheck --check-prefix RELAX %s
+
+# Fixups for %pcrel_hi / %pcrel_lo can be evaluated within a section,
+# regardless of the fragment containing the target address.
+
+function:
+.Lpcrel_label1:
+	auipc	a0, %pcrel_hi(other_function)
+	addi	a1, a0, %pcrel_lo(.Lpcrel_label1)
+# NORELAX: auipc	a0, 0
+# NORELAX-NOT: R_RISCV
+# NORELAX: addi	a1, a0, 16
+# NORELAX-NOT: R_RISCV
+
+# RELAX: auipc	a0, 0
+# RELAX: R_RISCV_PCREL_HI20	other_function
+# RELAX: R_RISCV_RELAX	*ABS*
+# RELAX: addi	a1, a0, 0
+# RELAX: R_RISCV_PCREL_LO12_I	.Lpcrel_label1
+# RELAX: R_RISCV_RELAX	*ABS*
+
+	.p2align	2   # Cause a new fragment be emitted here
+.Lpcrel_label2:
+	auipc	a0, %pcrel_hi(other_function)
+	addi	a1, a0, %pcrel_lo(.Lpcrel_label2)
+# NORELAX: auipc	a0, 0
+# NORELAX-NOT: R_RISCV
+# NORELAX: addi	a1, a0, 8
+# NORELAX-NOT: R_RISCV
+
+# RELAX: auipc	a0, 0
+# RELAX: R_RISCV_PCREL_HI20	other_function
+# RELAX: R_RISCV_RELAX	*ABS*
+# RELAX: addi	a1, a0, 0
+# RELAX: R_RISCV_PCREL_LO12_I	.Lpcrel_label2
+# RELAX: R_RISCV_RELAX	*ABS*
+
+	.type	other_function, at function
+other_function:
+	ret
+
Index: llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
===================================================================
--- llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
+++ llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp
@@ -64,11 +64,15 @@
     case RISCV::fixup_riscv_tls_gd_hi20:
       ShouldForce = true;
       break;
-    case RISCV::fixup_riscv_pcrel_hi20:
-      ShouldForce = T->getValue()->findAssociatedFragment() !=
-                    Fixup.getValue()->findAssociatedFragment();
+    case RISCV::fixup_riscv_pcrel_hi20: {
+      MCFragment *TFragment = T->getValue()->findAssociatedFragment();
+      MCFragment *FixupFragment = Fixup.getValue()->findAssociatedFragment();
+      assert(FixupFragment && "We should have a fragment for this fixup");
+      ShouldForce =
+          !TFragment || TFragment->getParent() != FixupFragment->getParent();
       break;
     }
+    }
     break;
   }
 


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