Generated assembly is a little better now, LLVM fixed two spurious movs

Author: dsharlet

README.md

@@ -341,34 +341,31 @@ For example, a matrix multiplication can be tiled like so:
   }
 ```
 
-This generates the following machine code(\*) for the inner loop using clang 11 with -O2 -ffast-math:
+This generates the following machine code(\*) for the inner loop using clang 18 with -O2 -ffast-math:
 ```assembly
-LBB8_7:
-  vmovaps %ymm12, %ymm13
-  vmovaps %ymm11, %ymm14
-  vbroadcastss  (%r13,%rcx,4), %ymm15
-  vmovups -64(%r9,%rdi,4), %ymm12
-  vmovups -32(%r9,%rdi,4), %ymm11
-  vmovups (%r9,%rdi,4), %ymm0
-  vfmadd231ps %ymm15, %ymm12, %ymm10
-  vfmadd231ps %ymm15, %ymm11, %ymm9
-  vfmadd231ps %ymm15, %ymm0, %ymm8
-  vbroadcastss  (%r14,%rcx,4), %ymm15
-  vfmadd231ps %ymm15, %ymm12, %ymm7
-  vfmadd231ps %ymm15, %ymm11, %ymm6
-  vfmadd231ps %ymm15, %ymm0, %ymm5
-  vbroadcastss  (%rsi,%rcx,4), %ymm15
-  vfmadd231ps %ymm15, %ymm12, %ymm4
-  vfmadd231ps %ymm15, %ymm11, %ymm3
-  vfmadd231ps %ymm15, %ymm0, %ymm2
-  vbroadcastss  (%rax,%rcx,4), %ymm15
-  vfmadd213ps %ymm13, %ymm15, %ymm12
-  vfmadd213ps %ymm14, %ymm15, %ymm11
-  vfmadd231ps %ymm15, %ymm0, %ymm1
-  incq  %rcx
-  addq  %rbx, %rdi
-  cmpq  %rcx, %rdx
-  jne LBB8_7
+vbroadcastss	(%rsi,%rdi,4), %ymm12
+vmovups	-64(%r12,%r15,4), %ymm13
+vmovups	-32(%r12,%r15,4), %ymm14
+vmovups	(%r12,%r15,4), %ymm15
+addq	%rbx, %r15
+vfmadd231ps	%ymm12, %ymm13, %ymm11
+vfmadd231ps	%ymm12, %ymm14, %ymm10
+vfmadd231ps	%ymm12, %ymm15, %ymm9
+vbroadcastss	(%r8,%rdi,4), %ymm12
+vfmadd231ps	%ymm12, %ymm13, %ymm8
+vfmadd231ps	%ymm12, %ymm14, %ymm7
+vfmadd231ps	%ymm12, %ymm15, %ymm6
+vbroadcastss	(%r10,%rdi,4), %ymm12
+vfmadd231ps	%ymm12, %ymm13, %ymm5
+vfmadd231ps	%ymm12, %ymm14, %ymm4
+vfmadd231ps	%ymm12, %ymm15, %ymm3
+vbroadcastss	(%rdx,%rdi,4), %ymm12
+incq	%rdi
+vfmadd231ps	%ymm13, %ymm12, %ymm2
+vfmadd231ps	%ymm14, %ymm12, %ymm1
+vfmadd231ps	%ymm12, %ymm15, %ymm0
+cmpq	%rdi, %r13
+jne	.LBB8_12
 ```
 This is **40-50x** faster than a naive C implementation of nested loops on my machine, and it should be within a factor of 2 of the peak possible performance.
 

examples/linear_algebra/matrix.cpp

@@ -125,32 +125,30 @@ NOINLINE void multiply_ein_reduce_matrix(
 // to keep all of the accumulators for the output in registers. This
 // generates an inner loop that looks like:
 //
-// LBB14_7:
-//   vmovaps %ymm12, %ymm13
-//   vmovaps %ymm11, %ymm14
-//   vbroadcastss    (%r9,%rax,4), %ymm15
-//   vmovups -64(%r11,%rcx,4), %ymm12
-//   vmovups -32(%r11,%rcx,4), %ymm11
-//   vmovups (%r11,%rcx,4), %ymm0
-//   vfmadd231ps     %ymm15, %ymm12, %ymm10
-//   vfmadd231ps     %ymm15, %ymm11, %ymm9
-//   vfmadd231ps     %ymm15, %ymm0, %ymm8
-//   vbroadcastss    (%r8,%rax,4), %ymm15
-//   vfmadd231ps     %ymm15, %ymm12, %ymm7
-//   vfmadd231ps     %ymm15, %ymm11, %ymm6
-//   vfmadd231ps     %ymm15, %ymm0, %ymm5
-//   vbroadcastss    (%rdx,%rax,4), %ymm15
-//   vfmadd231ps     %ymm15, %ymm12, %ymm4
-//   vfmadd231ps     %ymm15, %ymm11, %ymm3
-//   vfmadd231ps     %ymm15, %ymm0, %ymm2
-//   vbroadcastss    (%r15,%rax,4), %ymm15
-//   vfmadd213ps     %ymm13, %ymm15, %ymm12
-//   vfmadd213ps     %ymm14, %ymm15, %ymm11
-//   vfmadd231ps     %ymm15, %ymm0, %ymm1
-//   incq    %rax
-//   addq    %rsi, %rcx
-//   cmpq    %rax, %rbx
-//   jne     LBB14_7
+//.LBB8_12:
+//	 vbroadcastss	(%rsi,%rdi,4), %ymm12
+//	 vmovups	-64(%r12,%r15,4), %ymm13
+//	 vmovups	-32(%r12,%r15,4), %ymm14
+//	 vmovups	(%r12,%r15,4), %ymm15
+//	 addq	%rbx, %r15
+//	 vfmadd231ps	%ymm12, %ymm13, %ymm11
+//	 vfmadd231ps	%ymm12, %ymm14, %ymm10
+//	 vfmadd231ps	%ymm12, %ymm15, %ymm9
+//	 vbroadcastss	(%r8,%rdi,4), %ymm12
+//	 vfmadd231ps	%ymm12, %ymm13, %ymm8
+//	 vfmadd231ps	%ymm12, %ymm14, %ymm7
+//	 vfmadd231ps	%ymm12, %ymm15, %ymm6
+//	 vbroadcastss	(%r10,%rdi,4), %ymm12
+//	 vfmadd231ps	%ymm12, %ymm13, %ymm5
+//	 vfmadd231ps	%ymm12, %ymm14, %ymm4
+//	 vfmadd231ps	%ymm12, %ymm15, %ymm3
+//	 vbroadcastss	(%rdx,%rdi,4), %ymm12
+//	 incq	%rdi
+//	 vfmadd231ps	%ymm13, %ymm12, %ymm2
+//	 vfmadd231ps	%ymm14, %ymm12, %ymm1
+//	 vfmadd231ps	%ymm12, %ymm15, %ymm0
+//	 cmpq	%rdi, %r13
+//	 jne	.LBB8_12
 //
 // This appears to achieve ~70% of the peak theoretical throughput
 // of my machine.