From d85f65147aeb4009742bfe401c6070d920b71b3e Mon Sep 17 00:00:00 2001
From: Gui Cao <gcao@openjdk.org>
Date: Thu, 6 Feb 2025 09:31:54 +0000
Subject: [PATCH] 8349428: RISC-V: "bad alignment" with
 -XX:-AvoidUnalignedAccesses after JDK-8347489

Reviewed-by: fyang, mli
---
 .../cpu/riscv/c2_MacroAssembler_riscv.cpp     | 44 +++++++++++--------
 src/hotspot/cpu/riscv/stubGenerator_riscv.cpp | 12 ++++-
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp b/src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp
index c3296aeb76b..f52d5d7d12c 100644
--- a/src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp
+++ b/src/hotspot/cpu/riscv/c2_MacroAssembler_riscv.cpp
@@ -1461,12 +1461,14 @@ void C2_MacroAssembler::string_compare(Register str1, Register str2,
   {
     if (str1_isL == str2_isL) { // LL or UU
 #ifdef ASSERT
-      Label align_ok;
-      orr(t0, str1, str2);
-      andi(t0, t0, 0x7);
-      beqz(t0, align_ok);
-      stop("bad alignment");
-      bind(align_ok);
+      if (AvoidUnalignedAccesses) {
+        Label align_ok;
+        orr(t0, str1, str2);
+        andi(t0, t0, 0x7);
+        beqz(t0, align_ok);
+        stop("bad alignment");
+        bind(align_ok);
+      }
 #endif
       // load 8 bytes once to compare
       ld(tmp1, Address(str1));
@@ -1518,7 +1520,7 @@ void C2_MacroAssembler::string_compare(Register str1, Register str2,
     // main loop
     bind(NEXT_WORD);
     if (str1_isL == str2_isL) { // LL or UU
-      // both of the two loads are 8-byte aligned
+      // 8-byte aligned loads when AvoidUnalignedAccesses is enabled
       add(t0, str1, cnt2);
       ld(tmp1, Address(t0));
       add(t0, str2, cnt2);
@@ -1713,12 +1715,14 @@ void C2_MacroAssembler::arrays_equals(Register a1, Register a2,
   bltz(cnt1, SHORT);
 
 #ifdef ASSERT
-  Label align_ok;
-  orr(t0, a1, a2);
-  andi(t0, t0, 0x7);
-  beqz(t0, align_ok);
-  stop("bad alignment");
-  bind(align_ok);
+  if (AvoidUnalignedAccesses) {
+    Label align_ok;
+    orr(t0, a1, a2);
+    andi(t0, t0, 0x7);
+    beqz(t0, align_ok);
+    stop("bad alignment");
+    bind(align_ok);
+  }
 #endif
 
   // Main 8 byte comparison loop.
@@ -1817,12 +1821,14 @@ void C2_MacroAssembler::string_equals(Register a1, Register a2,
   bltz(cnt1, SHORT);
 
 #ifdef ASSERT
-  Label align_ok;
-  orr(t0, a1, a2);
-  andi(t0, t0, 0x7);
-  beqz(t0, align_ok);
-  stop("bad alignment");
-  bind(align_ok);
+  if (AvoidUnalignedAccesses) {
+    Label align_ok;
+    orr(t0, a1, a2);
+    andi(t0, t0, 0x7);
+    beqz(t0, align_ok);
+    stop("bad alignment");
+    bind(align_ok);
+  }
 #endif
 
   // Main 8 byte comparison loop.
diff --git a/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp b/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
index bb536c3e111..bef5638ed07 100644
--- a/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
+++ b/src/hotspot/cpu/riscv/stubGenerator_riscv.cpp
@@ -2458,7 +2458,15 @@ class StubGenerator: public StubCodeGenerator {
     assert((base_offset % (UseCompactObjectHeaders ? 4 :
                            (UseCompressedClassPointers ? 8 : 4))) == 0, "Must be");
 
-    // strL is 8-byte aligned
+#ifdef ASSERT
+    if (AvoidUnalignedAccesses) {
+      Label align_ok;
+      __ andi(t0, strL, 0x7);
+      __ beqz(t0, align_ok);
+      __ stop("bad alignment");
+      __ bind(align_ok);
+    }
+#endif
     __ ld(tmpLval, Address(strL));
     __ addi(strL, strL, wordSize);
 
@@ -2542,7 +2550,7 @@ class StubGenerator: public StubCodeGenerator {
       __ subi(cnt2, cnt2, wordSize / 2);
     }
 
-    // we are now 8-bytes aligned on strL
+    // we are now 8-bytes aligned on strL when AvoidUnalignedAccesses is true
     __ subi(cnt2, cnt2, wordSize * 2);
     __ bltz(cnt2, TAIL);
     __ bind(SMALL_LOOP); // smaller loop