PPC/s390: [wasm] Load register values from DebugBreak frame

Port ae03752f

Original Commit Message:

    This implements inspection of live registers on breakpoints in Liftoff.
    To that end, the frame pointer of the WasmDebugBreak frame is remembered
    when iterating the stack. Based on a platform-specific implementation of
    {WasmDebugBreakFrameConstants}, the offset of the respective register
    within that frame is computed, and the value is read from the frame.

    As a drive-by, the wasm debug side table is storing register codes as
    liftoff codes, which can also store register pairs (needed for i64 on
    32-bit platforms, and for SIMD, which is not supported yet).

R=clemensb@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I1f4a52c349bd57098f633c5fd641642695b6fe96
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2106294Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#66737}

src/execution/ppc/frame-constants-ppc.h

@@ -45,6 +45,27 @@ class WasmDebugBreakFrameConstants : public TypedFrameConstants {
       base::bits::CountPopulation(kPushedGpRegs);
   static constexpr int kNumPushedFpRegisters =
       base::bits::CountPopulation(kPushedFpRegs);
+
+  static constexpr int kLastPushedGpRegisterOffset =
+      -TypedFrameConstants::kFixedFrameSizeFromFp -
+      kSystemPointerSize * kNumPushedGpRegisters;
+  static constexpr int kLastPushedFpRegisterOffset =
+      kLastPushedGpRegisterOffset - kDoubleSize * kNumPushedFpRegisters;
+
+  // Offsets are fp-relative.
+  static int GetPushedGpRegisterOffset(int reg_code) {
+    DCHECK_NE(0, kPushedGpRegs & (1 << reg_code));
+    uint32_t lower_regs = kPushedGpRegs & ((uint32_t{1} << reg_code) - 1);
+    return kLastPushedGpRegisterOffset +
+           base::bits::CountPopulation(lower_regs) * kSystemPointerSize;
+  }
+
+  static int GetPushedFpRegisterOffset(int reg_code) {
+    DCHECK_NE(0, kPushedFpRegs & (1 << reg_code));
+    uint32_t lower_regs = kPushedFpRegs & ((uint32_t{1} << reg_code) - 1);
+    return kLastPushedFpRegisterOffset +
+           base::bits::CountPopulation(lower_regs) * kDoubleSize;
+  }
 };
 
 }  // namespace internal

src/execution/s390/frame-constants-s390.h

@@ -51,6 +51,27 @@ class WasmDebugBreakFrameConstants : public TypedFrameConstants {
       base::bits::CountPopulation(kPushedGpRegs);
   static constexpr int kNumPushedFpRegisters =
       base::bits::CountPopulation(kPushedFpRegs);
+
+  static constexpr int kLastPushedGpRegisterOffset =
+      -TypedFrameConstants::kFixedFrameSizeFromFp -
+      kSystemPointerSize * kNumPushedGpRegisters;
+  static constexpr int kLastPushedFpRegisterOffset =
+      kLastPushedGpRegisterOffset - kDoubleSize * kNumPushedFpRegisters;
+
+  // Offsets are fp-relative.
+  static int GetPushedGpRegisterOffset(int reg_code) {
+    DCHECK_NE(0, kPushedGpRegs & (1 << reg_code));
+    uint32_t lower_regs = kPushedGpRegs & ((uint32_t{1} << reg_code) - 1);
+    return kLastPushedGpRegisterOffset +
+           base::bits::CountPopulation(lower_regs) * kSystemPointerSize;
+  }
+
+  static int GetPushedFpRegisterOffset(int reg_code) {
+    DCHECK_NE(0, kPushedFpRegs & (1 << reg_code));
+    uint32_t lower_regs = kPushedFpRegs & ((uint32_t{1} << reg_code) - 1);
+    return kLastPushedFpRegisterOffset +
+           base::bits::CountPopulation(lower_regs) * kDoubleSize;
+  }
 };
 
 }  // namespace internal