Merge pull request #23948 from BruceForstall/Fix23920

Update maximum allowed arm prolog size

6 files changed, 34 insertions, 10 deletions

diff --git a/src/jit/codegenarmarch.cpp b/src/jit/codegenarmarch.cpp
index 55b3f0a7ba..add7b9867d 100644
--- a/src/jit/codegenarmarch.cpp
+++ b/src/jit/codegenarmarch.cpp
@@ -3849,7 +3849,9 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
 
         // Generate:
         //
-        //      mov rOffset, -pageSize
+        //      mov rOffset, -pageSize    // On arm, this turns out to be "movw r1, 0xf000; sxth r1, r1".
+        //                                // We could save 4 bytes in the prolog by using "movs r1, 0" at the
+        //                                // runtime expense of running a useless first loop iteration.
         //      mov rLimit, -frameSize
         // loop:
         //      ldr rTemp, [sp + rOffset] // rTemp = wzr on ARM64
diff --git a/src/jit/emit.h b/src/jit/emit.h
index 1308531a90..b429920c38 100644
--- a/src/jit/emit.h
+++ b/src/jit/emit.h
@@ -1374,7 +1374,7 @@ protected:
     void emitDispClsVar(CORINFO_FIELD_HANDLE fldHnd, ssize_t offs, bool reloc = false);
     void emitDispFrameRef(int varx, int disp, int offs, bool asmfm);
     void emitDispInsOffs(unsigned offs, bool doffs);
-    void emitDispInsHex(BYTE* code, size_t sz);
+    void emitDispInsHex(instrDesc* id, BYTE* code, size_t sz);
 
 #else // !DEBUG
 #define emitVarRefOffs 0
diff --git a/src/jit/emitarm.cpp b/src/jit/emitarm.cpp
index 3d7089bb8a..9e36efb4df 100644
--- a/src/jit/emitarm.cpp
+++ b/src/jit/emitarm.cpp
@@ -6778,7 +6778,7 @@ void emitter::emitDispGC(emitAttr attr)
  *  Display (optionally) the instruction encoding in hex
  */
 
-void emitter::emitDispInsHex(BYTE* code, size_t sz)
+void emitter::emitDispInsHex(instrDesc* id, BYTE* code, size_t sz)
 {
     // We do not display the instruction hex if we want diff-able disassembly
     if (!emitComp->opts.disDiffable)
@@ -6791,6 +6791,27 @@ void emitter::emitDispInsHex(BYTE* code, size_t sz)
         {
             printf("  %04X %04X", (*((unsigned short*)(code + 0))), (*((unsigned short*)(code + 2))));
         }
+        else
+        {
+            assert(sz == 0);
+
+            // At least display the encoding size of the instruction, even if not displaying its actual encoding.
+            insSize isz = emitInsSize(id->idInsFmt());
+            switch (isz)
+            {
+                case ISZ_16BIT:
+                    printf("  2B");
+                    break;
+                case ISZ_32BIT:
+                    printf("  4B");
+                    break;
+                case ISZ_48BIT:
+                    printf("  6B");
+                    break;
+                default:
+                    unreached();
+            }
+        }
     }
 }
 
@@ -6822,7 +6843,7 @@ void emitter::emitDispInsHelp(
 
     /* Display the instruction hex code */
 
-    emitDispInsHex(code, sz);
+    emitDispInsHex(id, code, sz);
 
     printf("      ");
 
diff --git a/src/jit/emitarm64.cpp b/src/jit/emitarm64.cpp
index afd5cf44e2..0345a361c8 100644
--- a/src/jit/emitarm64.cpp
+++ b/src/jit/emitarm64.cpp
@@ -10698,7 +10698,7 @@ void emitter::emitDispAddrRRExt(regNumber reg1, regNumber reg2, insOpts opt, boo
  *  Display (optionally) the instruction encoding in hex
  */
 
-void emitter::emitDispInsHex(BYTE* code, size_t sz)
+void emitter::emitDispInsHex(instrDesc* id, BYTE* code, size_t sz)
 {
     // We do not display the instruction hex if we want diff-able disassembly
     if (!emitComp->opts.disDiffable)
@@ -10709,6 +10709,7 @@ void emitter::emitDispInsHex(BYTE* code, size_t sz)
         }
         else
         {
+            assert(sz == 0);
             printf("              ");
         }
     }
@@ -10742,7 +10743,7 @@ void emitter::emitDispIns(
 
     /* Display the instruction hex code */
 
-    emitDispInsHex(pCode, sz);
+    emitDispInsHex(id, pCode, sz);
 
     printf("      ");
 
diff --git a/src/jit/emitxarch.cpp b/src/jit/emitxarch.cpp
index 6052b97493..f7b3c5baa4 100644
--- a/src/jit/emitxarch.cpp
+++ b/src/jit/emitxarch.cpp
@@ -8049,7 +8049,7 @@ void emitter::emitDispShift(instruction ins, int cnt)
  *  Display (optionally) the bytes for the instruction encoding in hex
  */
 
-void emitter::emitDispInsHex(BYTE* code, size_t sz)
+void emitter::emitDispInsHex(instrDesc* id, BYTE* code, size_t sz)
 {
     // We do not display the instruction hex if we want diff-able disassembly
     if (!emitComp->opts.disDiffable)
@@ -8216,7 +8216,7 @@ void emitter::emitDispIns(
     {
         /* Display the instruction hex code */
 
-        emitDispInsHex(code, sz);
+        emitDispInsHex(id, code, sz);
     }
 
     /* Display the instruction name */
diff --git a/src/jit/unwind.h b/src/jit/unwind.h
index a78df32f1f..06396f2a9a 100644
--- a/src/jit/unwind.h
+++ b/src/jit/unwind.h
@@ -20,8 +20,8 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 // You can increase this "max" number if necessary.
 
 #if defined(_TARGET_ARM_)
-const unsigned MAX_PROLOG_SIZE_BYTES = 40;
-const unsigned MAX_EPILOG_SIZE_BYTES = 40;
+const unsigned MAX_PROLOG_SIZE_BYTES = 44;
+const unsigned MAX_EPILOG_SIZE_BYTES = 44;
 #define UWC_END 0xFF // "end" unwind code
 #define UW_MAX_FRAGMENT_SIZE_BYTES (1U << 19)
 #define UW_MAX_CODE_WORDS_COUNT 15      // Max number that can be encoded in the "Code Words" field of the .pdata record