rts: Ensure that XMM registers are preserved on Win64

Previously we only preserved the bottom 64-bits of the callee-saved
128-bit XMM registers, in violation of the Win64 calling convention.
Fix this.

Fixes #21465.

3 files changed, 41 insertions, 30 deletions

diff --git a/compiler/GHC/CmmToAsm/X86/Regs.hs b/compiler/GHC/CmmToAsm/X86/Regs.hs
index cc880f6e98..38d4fdc422 100644
--- a/compiler/GHC/CmmToAsm/X86/Regs.hs
+++ b/compiler/GHC/CmmToAsm/X86/Regs.hs
@@ -382,9 +382,9 @@ callClobberedRegs platform
  | target32Bit platform = [eax,ecx,edx] ++ map regSingle (floatregnos platform)
  | platformOS platform == OSMinGW32
    = [rax,rcx,rdx,r8,r9,r10,r11]
-   -- Only xmm0-5 are caller-saves registers on 64bit windows.
-   -- ( https://docs.microsoft.com/en-us/cpp/build/register-usage )
-   -- For details check the Win64 ABI.
+   -- Only xmm0-5 are caller-saves registers on 64-bit windows.
+   -- For details check the Win64 ABI:
+   -- https://docs.microsoft.com/en-us/cpp/build/x64-software-conventions
    ++ map xmm [0  .. 5]
  | otherwise
     -- all xmm regs are caller-saves
diff --git a/rts/StgCRun.c b/rts/StgCRun.c
index 7f5b6d169b..4fefc326e5 100644
--- a/rts/StgCRun.c
+++ b/rts/StgCRun.c
@@ -115,8 +115,9 @@ StgFunPtr StgReturn(void)
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  * On X86 (both 32bit and 64bit) we keep the stack aligned on function calls at
  * a 16-byte boundary. This is done because on a number of architectures the
- * ABI requires this (x64, Mac OSX 32bit/64bit) as well as interfacing with
- * other libraries through the FFI.
+ * ABI requires this (e.g. the System V AMD64 ABI, Mac OS X 32-bit/64-bit ABIs,
+ * and the Win64 ABI) as well as interfacing with * other libraries through the
+ * FFI.
  *
  * As part of this arrangement we must maintain the stack at a 16-byte boundary
  * - word_size-bytes (so 16n - 4 for i386 and 16n - 8 for x64) on entry to a
@@ -405,19 +406,27 @@ StgRunIsImplementedInAssembler(void)
          * Additional callee saved registers on Win64. This must match
          * callClobberedRegisters in compiler/GHC/CmmToAsm/X86/Regs.hs as
          * both represent the Win64 calling convention.
+         *
+         * Note that we must save the entire 128-bit width of the XMM
+         * registers, as noted in #21465. Moreover, note that, due to the
+         * presence of the return address on the stack, %rsp+8 is
+         * 16-byte aligned. Since MOVAPS requires memory operands to be aligned
+         * to 16-bytes, we must add a word of padding here.
          */
-        "movq %%rdi,48(%%rax)\n\t"
-        "movq %%rsi,56(%%rax)\n\t"
-        "movq %%xmm6,  64(%%rax)\n\t"
-        "movq %%xmm7,  72(%%rax)\n\t"
-        "movq %%xmm8,  80(%%rax)\n\t"
-        "movq %%xmm9,  88(%%rax)\n\t"
-        "movq %%xmm10, 96(%%rax)\n\t"
-        "movq %%xmm11,104(%%rax)\n\t"
-        "movq %%xmm12,112(%%rax)\n\t"
-        "movq %%xmm13,120(%%rax)\n\t"
-        "movq %%xmm14,128(%%rax)\n\t"
-        "movq %%xmm15,136(%%rax)\n\t"
+        "movq %%rdi,   48(%%rax)\n\t"
+        "movq %%rsi,   56(%%rax)\n\t"
+        /* 8 bytes of padding for alignment */
+        "movaps %%xmm6,  72(%%rax)\n\t"
+        "movaps %%xmm7,  88(%%rax)\n\t"
+        "movaps %%xmm8, 104(%%rax)\n\t"
+        "movaps %%xmm9, 120(%%rax)\n\t"
+        "movaps %%xmm10,136(%%rax)\n\t"
+        "movaps %%xmm11,152(%%rax)\n\t"
+        "movaps %%xmm12,168(%%rax)\n\t"
+        "movaps %%xmm13,184(%%rax)\n\t"
+        "movaps %%xmm14,200(%%rax)\n\t"
+        "movaps %%xmm15,216(%%rax)\n\t"
+        /* 8 bytes of padding for alignment */
 #endif
 
 #if defined(ENABLE_UNWINDING)
@@ -506,18 +515,20 @@ StgRunIsImplementedInAssembler(void)
         "movq 32(%%rsp),%%r14\n\t"
         "movq 40(%%rsp),%%r15\n\t"
 #if defined(mingw32_HOST_OS)
-        "movq  48(%%rsp),%%rdi\n\t"
-        "movq  56(%%rsp),%%rsi\n\t"
-        "movq  64(%%rsp),%%xmm6\n\t"
-        "movq  72(%%rsp),%%xmm7\n\t"
-        "movq  80(%%rsp),%%xmm8\n\t"
-        "movq  88(%%rsp),%%xmm9\n\t"
-        "movq  96(%%rsp),%%xmm10\n\t"
-        "movq 104(%%rsp),%%xmm11\n\t"
-        "movq 112(%%rsp),%%xmm12\n\t"
-        "movq 120(%%rsp),%%xmm13\n\t"
-        "movq 128(%%rsp),%%xmm14\n\t"
-        "movq 136(%%rsp),%%xmm15\n\t"
+        "movq 48(%%rsp),%%rdi\n\t"
+        "movq 56(%%rsp),%%rsi\n\t"
+        /* 8 bytes of padding for alignment */
+        "movaps  72(%%rsp),%%xmm6\n\t"
+        "movaps  88(%%rsp),%%xmm7\n\t"
+        "movaps 104(%%rsp),%%xmm8\n\t"
+        "movaps 120(%%rsp),%%xmm9\n\t"
+        "movaps 136(%%rsp),%%xmm10\n\t"
+        "movaps 152(%%rsp),%%xmm11\n\t"
+        "movaps 168(%%rsp),%%xmm12\n\t"
+        "movaps 184(%%rsp),%%xmm13\n\t"
+        "movaps 200(%%rsp),%%xmm14\n\t"
+        "movaps 216(%%rsp),%%xmm15\n\t"
+        /* 8 bytes of padding for alignment */
 #endif
         "addq %1, %%rsp\n\t"
         "retq"
diff --git a/rts/include/rts/Constants.h b/rts/include/rts/Constants.h
index b601999f88..3bf5a7a2d5 100644
--- a/rts/include/rts/Constants.h
+++ b/rts/include/rts/Constants.h
@@ -123,7 +123,7 @@
    -------------------------------------------------------------------------- */
 #if defined(x86_64_HOST_ARCH)
 #  if defined(mingw32_HOST_OS)
-#    define STG_RUN_STACK_FRAME_SIZE 144
+#    define STG_RUN_STACK_FRAME_SIZE 240
 #  else
 #    define STG_RUN_STACK_FRAME_SIZE 48
 #  endif